diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/IXLWorksheet.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/IXLWorksheet.cs
index 17fbe26..0798d6c 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/IXLWorksheet.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/IXLWorksheet.cs
@@ -26,6 +26,12 @@
         /// </summary>
         Int32 SheetIndex { get; set; }
         /// <summary>
+        /// Gets or sets the position of the sheet.
+        /// <para>When setting the Position all other sheets' positions are shifted accordingly.</para>
+        /// </summary>
+        Int32 Position { get; set; }
+
+        /// <summary>
         /// Gets an object to manipulate the sheet's print options.
         /// </summary>
         IXLPageSetup PageSetup { get; }
@@ -239,5 +245,12 @@
         IXLSheetView SheetView { get; }
 
         IXLTables Tables { get; }
+
+        IXLWorksheet CopyTo(String newSheetName);
+        IXLWorksheet CopyTo(String newSheetName, Int32 position);
+        IXLWorksheet CopyTo(XLWorkbook workbook, String newSheetName);
+        IXLWorksheet CopyTo(XLWorkbook workbook, String newSheetName, Int32 position);
+
+        IXLRange RangeUsed();
     }
 }
diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/IXLWorksheets.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/IXLWorksheets.cs
index d312566..2c19286 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/IXLWorksheets.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/IXLWorksheets.cs
@@ -10,6 +10,7 @@
         IXLWorksheet Worksheet(String sheetName);
         IXLWorksheet Worksheet(Int32 sheetIndex);
         IXLWorksheet Add(String sheetName);
+        IXLWorksheet Add(String sheetName, Int32 position);
         void Delete(String sheetName);
         void Delete(Int32 sheetIndex);
     }
diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/Ranges/IXLRange.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/Ranges/IXLRange.cs
index 5b3a178..9a989f8 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/Ranges/IXLRange.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/Ranges/IXLRange.cs
@@ -213,6 +213,8 @@
         IXLTable AsTable(String name);
         IXLTable CreateTable();
         IXLTable CreateTable(String name);
+
+        IXLRange RangeUsed();
     }
 }
 
diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/Ranges/XLRange.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/Ranges/XLRange.cs
index 8ecf094..95eba21 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/Ranges/XLRange.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/Ranges/XLRange.cs
@@ -424,6 +424,7 @@
         {
             return new XLTable(this, false);
         }
+
         public IXLTable AsTable(String name)
         {
             return new XLTable(this, name, false);
@@ -433,11 +434,11 @@
         {
             return new XLTable(this, true);
         }
+
         public IXLTable CreateTable(String name)
         {
             return new XLTable(this, name, true);
         }
-
         #endregion
     }
 }
diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/Ranges/XLRangeBase.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/Ranges/XLRangeBase.cs
index 1f7c42f..0490307 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/Ranges/XLRangeBase.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/Ranges/XLRangeBase.cs
@@ -845,5 +845,10 @@
                 }
             }
         }
+
+        public IXLRange RangeUsed()
+        {
+            return this.Range(this.FirstCellUsed(), this.LastCellUsed());
+        }
     }
 }
diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/XLAddress.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/XLAddress.cs
index 7848a04..33f0a13 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/XLAddress.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/XLAddress.cs
@@ -3,6 +3,7 @@
 using System.Linq;
 using System.Text;
 using System.Text.RegularExpressions;
+using System.Globalization;
 
 namespace ClosedXML.Excel
 {
@@ -61,12 +62,12 @@
             if (fixedRow)
             {
                 columnLetter = cellAddressString.Substring(startPos, rowPos - 1);
-                rowNumber = Int32.Parse(cellAddressString.Substring(rowPos + 1));
+                rowNumber = Int32.Parse(cellAddressString.Substring(rowPos + 1), nfi);
             }
             else
             {
                 columnLetter = cellAddressString.Substring(startPos, rowPos);
-                rowNumber = Int32.Parse(cellAddressString.Substring(rowPos));
+                rowNumber = Int32.Parse(cellAddressString.Substring(rowPos), nfi);
             }
 
             columnNumber = 0;
@@ -83,7 +84,7 @@
         public static Int32 GetColumnNumberFromLetter(String columnLetter)
         {
             if (columnLetter[0] <= '9')
-                return Int32.Parse(columnLetter);
+                return Int32.Parse(columnLetter, nfi);
 
             columnLetter = columnLetter.ToUpper();
             var length = columnLetter.Length;
@@ -148,7 +149,7 @@
             while (cellAddressString[rowPos] > '9')
                 rowPos++;
 
-                return Int32.Parse(cellAddressString.Substring(rowPos));
+                return Int32.Parse(cellAddressString.Substring(rowPos), nfi);
         }
 
         public static Int32 GetColumnNumberFromAddress1(String cellAddressString)
@@ -168,11 +169,11 @@
 
             if (cellAddressString[rowPos] == '$')
             {
-                return Int32.Parse(cellAddressString.Substring(rowPos + 1));
+                return Int32.Parse(cellAddressString.Substring(rowPos + 1), nfi);
             }
             else
             {
-                return Int32.Parse(cellAddressString.Substring(rowPos));
+                return Int32.Parse(cellAddressString.Substring(rowPos), nfi);
             }
         }
 
@@ -260,21 +261,30 @@
         #endregion
 
         #region Overrides
+        private static NumberFormatInfo nfi = CultureInfo.InvariantCulture.NumberFormat;
         public override string ToString()
         {
-            var sb = new StringBuilder();
-            if (FixedColumn) sb.Append("$");
-            sb.Append(ColumnLetter);
-            if (FixedRow) sb.Append("$");
-            sb.Append(RowNumber.ToString());
-            return sb.ToString();
+            //var sb = new StringBuilder();
+            //if (FixedColumn) sb.Append("$");
+            //sb.Append(ColumnLetter);
+            //if (FixedRow) sb.Append("$");
+            //sb.Append(rowNumber.ToString());
+            //return sb.ToString();
+            
+            String retVal = ColumnLetter;
+            if (fixedColumn)
+                retVal = "$" + retVal;
+            if (fixedRow)
+                retVal += "$";
+            retVal += rowNumber.ToStringLookup();
+            return retVal;
         }
         #endregion
 
         #region Methods
         public string GetTrimmedAddress()
         {
-            return ColumnLetter + rowNumber.ToString();
+            return ColumnLetter + rowNumber.ToStringLookup();
         }
         #endregion
 
diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook.cs
index 323a090..b8e4b53 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook.cs
@@ -296,5 +296,14 @@
         }
 
         #endregion
+
+        public IXLWorksheet Worksheet(String name)
+        {
+            return Worksheets.Worksheet(name);
+        }
+        public IXLWorksheet Worksheet(Int32 sheetIndex)
+        {
+            return Worksheets.Worksheet(sheetIndex);
+        }
     }
 }
diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Load.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Load.cs
index cbd38a5..0759614 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Load.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Load.cs
@@ -103,7 +103,7 @@
                     var pane = (Pane)sheetView.Descendants<Pane>().FirstOrDefault();
                     if (pane != null)
                     {
-                        if (pane.State != null && pane.State == PaneStateValues.FrozenSplit)
+                        if (pane.State != null && (pane.State == PaneStateValues.FrozenSplit || pane.State == PaneStateValues.Frozen))
                         {
                             if (pane.HorizontalSplit != null)
                                 ws.SheetView.SplitColumn = (Int32)pane.HorizontalSplit.Value;
@@ -582,11 +582,11 @@
                 if (alignment.Horizontal != null)
                     xlStylized.InnerStyle.Alignment.Horizontal = alignmentHorizontalValues.Single(a => a.Value == alignment.Horizontal).Key;
                 if (alignment.Indent != null)
-                    xlStylized.InnerStyle.Alignment.Indent = (Int32)alignment.Indent.Value;
+                    xlStylized.InnerStyle.Alignment.Indent = Int32.Parse(alignment.Indent.ToString());
                 if (alignment.JustifyLastLine != null)
                     xlStylized.InnerStyle.Alignment.JustifyLastLine = alignment.JustifyLastLine;
                 if (alignment.ReadingOrder != null)
-                    xlStylized.InnerStyle.Alignment.ReadingOrder = (XLAlignmentReadingOrderValues)(Int32)alignment.ReadingOrder.Value ;
+                    xlStylized.InnerStyle.Alignment.ReadingOrder = (XLAlignmentReadingOrderValues)Int32.Parse(alignment.ReadingOrder.ToString());
                 if (alignment.RelativeIndent != null)
                     xlStylized.InnerStyle.Alignment.RelativeIndent = alignment.RelativeIndent;
                 if (alignment.ShrinkToFit != null)
@@ -672,18 +672,17 @@
                 if (fontColor.HasValue)
                     xlStylized.InnerStyle.Font.FontColor = fontColor;
 
-                if (font.FontFamilyNumbering != null)
-                    if (font.FontFamilyNumbering.Val.HasValue)
-                        xlStylized.InnerStyle.Font.FontFamilyNumbering = (XLFontFamilyNumberingValues)font.FontFamilyNumbering.Val.Value;
+                if (font.FontFamilyNumbering != null && ((FontFamilyNumbering)font.FontFamilyNumbering).Val != null)
+                    xlStylized.InnerStyle.Font.FontFamilyNumbering = (XLFontFamilyNumberingValues)Int32.Parse(((FontFamilyNumbering)font.FontFamilyNumbering).Val.ToString());
                 if (font.FontName != null)
                 {
-                    if (font.FontName.Val != null)
-                        xlStylized.InnerStyle.Font.FontName = font.FontName.Val;
+                    if (((FontName)font.FontName).Val != null)
+                        xlStylized.InnerStyle.Font.FontName = ((FontName)font.FontName).Val;
                 }
                 if (font.FontSize != null)
                 {
-                    if (font.FontSize.Val != null)
-                        xlStylized.InnerStyle.Font.FontSize = font.FontSize.Val;
+                    if (((FontSize)font.FontSize).Val != null)
+                        xlStylized.InnerStyle.Font.FontSize = ((FontSize)font.FontSize).Val;
                 }
 
                 xlStylized.InnerStyle.Font.Italic = GetBoolean(font.Italic);
diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Save.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Save.cs
index 760771d..34c8138 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Save.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Save.cs
@@ -595,7 +595,10 @@
 
             foreach (var xlSheet in Worksheets.Cast<XLWorksheet>().Where(w => w.SheetId == 0).OrderBy(w => w.SheetIndex))
             {
-                var rId = relId.GetNext(RelType.Workbook);
+                String rId = relId.GetNext(RelType.Workbook);
+                while (Worksheets.Cast<XLWorksheet>().Where(w=>w.SheetId == Int32.Parse(rId.Substring(3))).Any())
+                    rId = relId.GetNext(RelType.Workbook);
+
                 xlSheet.SheetId = Int32.Parse(rId.Substring(3));
                 xlSheet.RelId = rId;
                 workbook.Sheets.Append(new Sheet() { Name = xlSheet.Name, Id = rId, SheetId = (UInt32)xlSheet.SheetId });
@@ -1577,6 +1580,9 @@
 
                 columns = worksheetPart.Worksheet.Elements<Columns>().First();
 
+                Dictionary<UInt32, Column> sheetColumnsByMin = columns.Elements<Column>().ToDictionary(c => c.Min.Value, c => c);
+                //Dictionary<UInt32, Column> sheetColumnsByMax = columns.Elements<Column>().ToDictionary(c => c.Max.Value, c => c);
+
                 Int32 minInColumnsCollection;
                 Int32 maxInColumnsCollection;
                 if (xlWorksheet.Internals.ColumnsCollection.Count > 0)
@@ -1607,7 +1613,7 @@
                             CustomWidth = true
                         };
 
-                        UpdateColumn(column, columns);
+                        UpdateColumn(column, columns, sheetColumnsByMin); //, sheetColumnsByMax);
                     }
                 }
 
@@ -1644,7 +1650,7 @@
                     if (collapsed) column.Collapsed = true;
                     if (outlineLevel > 0) column.OutlineLevel = (byte)outlineLevel;
 
-                    UpdateColumn(column, columns);
+                    UpdateColumn(column, columns, sheetColumnsByMin); //, sheetColumnsByMax);
                 }
 
                 foreach (var col in columns.Elements<Column>().Where(c => c.Min > (UInt32)(maxInColumnsCollection)).OrderBy(c => c.Min.Value))
@@ -1668,6 +1674,8 @@
                     };
                     columns.Append(column);
                 }
+
+                CollapseColumns(columns, sheetColumnsByMin);
             }
             #endregion
 
@@ -1772,11 +1780,12 @@
                         var dataType = opCell.DataType;
                         var cellReference = ((XLAddress)opCell.Address).GetTrimmedAddress();
 
-                        Boolean isNewCell = false;
+                        //Boolean isNewCell = false;
+                        
                         Cell cell = row.Elements<Cell>().FirstOrDefault(c => c.CellReference.Value == cellReference);
                         if (cell == null)
                         {
-                            isNewCell = true;
+                            //isNewCell = true;
                             cell = new Cell() { CellReference = cellReference };
                             if (row.Elements<Cell>().Count() == 0)
                             {
@@ -1824,10 +1833,10 @@
                             {
                                 if (StringExtensions.IsNullOrWhiteSpace(opCell.InnerText))
                                 {
-                                    if (isNewCell)
-                                        cellValue = null;
-                                    else
-                                        cellValue.Text = String.Empty;
+                                    //if (isNewCell)
+                                    cellValue = null;
+                                    //else
+                                    //    cellValue.Text = String.Empty;
                                 }
                                 else
                                 {
@@ -1857,7 +1866,9 @@
             }
             #endregion
 
-            var phoneticProperties = worksheetPart.Worksheet.Elements<PhoneticProperties>().FirstOrDefault();
+            var autoFilter = worksheetPart.Worksheet.Elements<AutoFilter>().FirstOrDefault();
+
+            CustomSheetViews customSheetViews = worksheetPart.Worksheet.Elements<CustomSheetViews>().FirstOrDefault();
 
             #region MergeCells
             MergeCells mergeCells = null;
@@ -1866,8 +1877,10 @@
                 if (worksheetPart.Worksheet.Elements<MergeCells>().Count() == 0)
                 {
                     OpenXmlElement previousElement;
-                    if (phoneticProperties != null)
-                        previousElement = phoneticProperties;
+                    if (customSheetViews != null)
+                        previousElement = customSheetViews;
+                    else if (autoFilter != null)
+                        previousElement = autoFilter;
                     else if (sheetData != null)
                         previousElement = sheetData;
                     else if (columns != null)
@@ -1895,6 +1908,8 @@
             }
             #endregion
 
+            var phoneticProperties = worksheetPart.Worksheet.Elements<PhoneticProperties>().FirstOrDefault();
+
             var hyperlinks = worksheetPart.Worksheet.Elements<Hyperlinks>().FirstOrDefault();
 
             #region PrintOptions
@@ -1904,10 +1919,14 @@
                 OpenXmlElement previousElement;
                 if (hyperlinks != null)
                     previousElement = hyperlinks;
-                else if (mergeCells != null)
-                    previousElement = mergeCells;
                 else if (phoneticProperties != null)
                     previousElement = phoneticProperties;
+                else if (mergeCells != null)
+                    previousElement = mergeCells;
+                else if (customSheetViews != null)
+                    previousElement = customSheetViews;
+                else if (autoFilter != null)
+                    previousElement = autoFilter;
                 else if (sheetData != null)
                     previousElement = sheetData;
                 else if (columns != null)
@@ -1934,10 +1953,14 @@
                     previousElement = printOptions;
                 else if (hyperlinks != null)
                     previousElement = hyperlinks;
-                else if (mergeCells != null)
-                    previousElement = mergeCells;
                 else if (phoneticProperties != null)
                     previousElement = phoneticProperties;
+                else if (mergeCells != null)
+                    previousElement = mergeCells;
+                else if (customSheetViews != null)
+                    previousElement = customSheetViews;
+                else if (autoFilter != null)
+                    previousElement = autoFilter;
                 else if (sheetData != null)
                     previousElement = sheetData;
                 else if (columns != null)
@@ -2163,23 +2186,75 @@
             #endregion
         }
 
+        private void CollapseColumns(Columns columns, Dictionary<uint, Column> sheetColumns)
+        {
+            UInt32 lastMax = 1;
+            UInt32 lastMin = 1;
+            Int32 count = sheetColumns.Count;
+            foreach (var kp in sheetColumns.OrderBy(kp => kp.Key))
+            {
+                if (kp.Key < count && ColumnsAreEqual(kp.Value, sheetColumns[kp.Key + 1]))
+                {
+                    lastMax = kp.Key;
+                }
+                else
+                {
+                    var newColumn = (Column)kp.Value.CloneNode(true);
+                    newColumn.Min = lastMin;
+                    var columnsToRemove = new List<Column>();
+                    foreach (var c in columns.Elements<Column>().Where(co => co.Min >= newColumn.Min && co.Max <= newColumn.Max).Select(co => co))
+                    {
+                        columnsToRemove.Add(c);
+                    }
+                    columnsToRemove.ForEach(c => columns.RemoveChild(c));
+
+                    columns.Append(newColumn);
+                    
+                    lastMin = kp.Key + 1;
+                }
+                
+            }
+        }
+
+
+
         private Double GetColumnWidth(Double columnWidth)
         {
             return columnWidth + 0.71;
         }
 
-        private void UpdateColumn(Column column, Columns columns)
+        private void UpdateColumn(Column column, Columns columns, Dictionary<UInt32, Column> sheetColumnsByMin)//, Dictionary<UInt32, Column> sheetColumnsByMax)
         {
+            UInt32 co = column.Min.Value;
             Column newColumn;
-            Column existingColumn = columns.Elements<Column>().FirstOrDefault(c => c.Min.Value == column.Min.Value);
-            if (existingColumn == null)
+            Column existingColumn; // = columns.Elements<Column>().FirstOrDefault(c => c.Min.Value == column.Min.Value);
+            if (!sheetColumnsByMin.ContainsKey(co))
             {
+                //if (sheetColumnsByMin.ContainsKey(co + 1) && ColumnsAreEqual(column, sheetColumnsByMin[co + 1]))
+                //{
+                //    var thisColumn = sheetColumnsByMin[co + 1];
+                //    thisColumn.Min -= 1;
+                //    sheetColumnsByMin.Remove(co + 1);
+                //    sheetColumnsByMin.Add(co, thisColumn);
+                //}
+                //else if (sheetColumnsByMax.ContainsKey(co - 1) && ColumnsAreEqual(column, sheetColumnsByMin[co - 1]))
+                //{
+                //    var thisColumn = sheetColumnsByMin[co - 1];
+                //    thisColumn.Max += 1;
+                //    sheetColumnsByMax.Remove(co - 1);
+                //    sheetColumnsByMax.Add(co, thisColumn);
+                //}
+                //else
+                //{
                 newColumn = (Column)column.CloneNode(true);
-                //newColumn = new Column() { InnerXml = column.InnerXml };
                 columns.Append(newColumn);
+                sheetColumnsByMin.Add(co, newColumn);
+                //    sheetColumnsByMax.Add(co, newColumn);
+                //}
             }
             else
             {
+                existingColumn = sheetColumnsByMin[column.Min.Value];
                 newColumn = (Column)existingColumn.CloneNode(true);
                 //newColumn = new Column() { InnerXml = existingColumn.InnerXml };
                 newColumn.Min = column.Min;
@@ -2203,6 +2278,7 @@
                 else
                     newColumn.OutlineLevel = null;
 
+                sheetColumnsByMin.Remove(column.Min.Value);
                 if (existingColumn.Min + 1 > existingColumn.Max)
                 {
                     //existingColumn.Min = existingColumn.Min + 1;
@@ -2210,16 +2286,32 @@
                     //existingColumn.Remove();
                     columns.RemoveChild(existingColumn);
                     columns.Append(newColumn);
+                    sheetColumnsByMin.Add(newColumn.Min.Value, newColumn);
                 }
                 else
                 {
                     //columns.InsertBefore(existingColumn, newColumn);
                     columns.Append(newColumn);
+                    sheetColumnsByMin.Add(newColumn.Min.Value, newColumn);
                     existingColumn.Min = existingColumn.Min + 1;
+                    sheetColumnsByMin.Add(existingColumn.Min.Value, existingColumn);
                 }
             }
 
         }
+
+        private bool ColumnsAreEqual(Column column, Column column_2)
+        {
+            return
+                column.Style.Value == column_2.Style.Value
+                && column.Width.Value == column_2.Width.Value
+                && ((column.Hidden == null && column_2.Hidden == null)
+                    || (column.Hidden != null && column_2.Hidden != null && column.Hidden.Value == column_2.Hidden.Value))
+                && ((column.Collapsed == null && column_2.Collapsed == null)
+                    || (column.Collapsed != null && column_2.Collapsed != null && column.Collapsed.Value == column_2.Collapsed.Value))
+                && ((column.OutlineLevel == null && column_2.OutlineLevel == null)
+                    || (column.OutlineLevel != null && column_2.OutlineLevel != null && column.OutlineLevel.Value == column_2.OutlineLevel.Value));
+        }
         #endregion
 
         private void GenerateCalculationChainPartContent(WorkbookPart workbookPart)
@@ -2239,7 +2331,7 @@
                     var calculationCells = calculationChain.Elements<CalculationCell>().Where(
                         cc => cc.CellReference != null && cc.CellReference == c.Address.ToString()).Select(cc=>cc);
                     Boolean addNew = true;
-                    if (calculationCells.Count() > 0)
+                    if (calculationCells.FirstOrDefault() != null)
                     {
                         calculationCells.Where(cc=>cc.SheetId == null).Select(cc=>cc).ForEach(cc=>calculationChain.RemoveChild(cc));
                         var cCell = calculationCells.FirstOrDefault(cc=>cc.SheetId == worksheet.SheetId);
@@ -2257,17 +2349,17 @@
                     }
                 }
 
-                            var cCellsToRemove = new List<CalculationCell>();
-            var m = from cc in calculationChain.Elements<CalculationCell>()
-                    where cc.SheetId == null 
-                        && calculationChain.Elements<CalculationCell>()
-                        .Where(c1 => c1.SheetId != null)
-                        .Select(c1 => c1.CellReference.Value)
-                        .Contains(cc.CellReference.Value)
-                        || worksheet.Internals.CellsCollection.Where(kp=>kp.Key.ToString() == cc.CellReference.Value && StringExtensions.IsNullOrWhiteSpace(kp.Value.FormulaA1)).Any()
-                    select cc;
-            m.ForEach(cc => cCellsToRemove.Add(cc));
-            cCellsToRemove.ForEach(cc=>calculationChain.RemoveChild(cc));
+                var cCellsToRemove = new List<CalculationCell>();
+                var m = from cc in calculationChain.Elements<CalculationCell>()
+                        where cc.SheetId == null 
+                            && calculationChain.Elements<CalculationCell>()
+                            .Where(c1 => c1.SheetId != null)
+                            .Select(c1 => c1.CellReference.Value)
+                            .Contains(cc.CellReference.Value)
+                            || worksheet.Internals.CellsCollection.Where(kp=>kp.Key.ToString() == cc.CellReference.Value && StringExtensions.IsNullOrWhiteSpace(kp.Value.FormulaA1)).Any()
+                        select cc;
+                m.ForEach(cc => cCellsToRemove.Add(cc));
+                cCellsToRemove.ForEach(cc=>calculationChain.RemoveChild(cc));
             }
 
             if (calculationChain.Count() == 0)
diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorksheet.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorksheet.cs
index 98dcd9d..52e41fb 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorksheet.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorksheet.cs
@@ -175,7 +175,17 @@
                 sheetIndex = value;
             }
         }
-
+        public Int32 Position
+        {
+            get
+            {
+                return sheetIndex + 1;
+            }
+            set
+            {
+                SheetIndex = value - 1;
+            }
+        }
         public IXLPageSetup PageSetup { get; private set; }
         public IXLOutline Outline { get; private set; }
 
@@ -502,6 +512,31 @@
         public IXLSheetView SheetView { get; private set; }
         public IXLTables Tables { get; private set; }
 
+        public IXLWorksheet CopyTo(String newSheetName)
+        {
+            return CopyTo(this.workbook, newSheetName, workbook.Worksheets.Count() + 1);
+        }
+
+        public IXLWorksheet CopyTo(String newSheetName, Int32 position)
+        {
+            return CopyTo(this.workbook, newSheetName, position);
+        }
+
+        public IXLWorksheet CopyTo(XLWorkbook workbook, String newSheetName)
+        {
+            return CopyTo(workbook, newSheetName, workbook.Worksheets.Count() + 1);
+        }
+
+        public IXLWorksheet CopyTo(XLWorkbook workbook, String newSheetName, Int32 position)
+        {
+            var ws = (XLWorksheet)workbook.Worksheets.Add(newSheetName, position);
+            this.Internals.CellsCollection.ForEach(kp => ws.Internals.CellsCollection.Add(kp));
+            this.Internals.ColumnsCollection.ForEach(kp => ws.Internals.ColumnsCollection.Add(kp));
+            this.Internals.MergedRanges.ForEach(kp => ws.Internals.MergedRanges.Add(kp));
+            this.Internals.RowsCollection.ForEach(kp => ws.Internals.RowsCollection.Add(kp));
+            return ws;
+        }
+
         #region Outlines
         private Dictionary<Int32, Int32> columnOutlineCount = new Dictionary<Int32, Int32>();
         public void IncrementColumnOutline(Int32 level)
diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorksheets.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorksheets.cs
index 21deb40..a67a02f 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorksheets.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorksheets.cs
@@ -42,6 +42,13 @@
             return sheet;
         }
 
+        public IXLWorksheet Add(String sheetName, Int32 position)
+        {
+            var ws = Add(sheetName);
+            ws.Position = position;
+            return ws;
+        }
+
         public void Delete(String sheetName)
         {
             Delete(worksheets[sheetName].SheetIndex);
diff --git a/ClosedXML/ClosedXML/ClosedXML/Extensions.cs b/ClosedXML/ClosedXML/ClosedXML/Extensions.cs
index 9d60bea..9f0de2d 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Extensions.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Extensions.cs
@@ -3,6 +3,7 @@
 using System.Linq;
 using System.Text;
 using System.Drawing;
+using System.Globalization;
 
 namespace ClosedXML
 {
@@ -110,5 +111,19 @@
             return true;
         }
     }
+
+    public static class IntegerExtensions
+    {
+        private static NumberFormatInfo nfi = CultureInfo.InvariantCulture.NumberFormat;
+        private static Dictionary<Int32, String> intToString = new Dictionary<int, string>();
+        public static String ToStringLookup(this Int32 value)
+        {
+            if (!intToString.ContainsKey(value))
+            {
+                intToString.Add(value, value.ToString(nfi));
+            }
+            return intToString[value];
+        }
+    }
 }
 
diff --git a/ClosedXML/ClosedXML/ClosedXML_Examples/ClosedXML_Examples.csproj b/ClosedXML/ClosedXML/ClosedXML_Examples/ClosedXML_Examples.csproj
index f658c7d..20d97b6 100644
--- a/ClosedXML/ClosedXML/ClosedXML_Examples/ClosedXML_Examples.csproj
+++ b/ClosedXML/ClosedXML/ClosedXML_Examples/ClosedXML_Examples.csproj
@@ -58,6 +58,7 @@
     <Compile Include="Misc\AdjustToContents.cs" />
     <Compile Include="Misc\Collections.cs" />
     <Compile Include="Misc\BlankCells.cs" />
+    <Compile Include="Misc\CopyingWorksheets.cs" />
     <Compile Include="Misc\FreezePanes.cs" />
     <Compile Include="PageSetup\TwoPages.cs" />
     <Compile Include="Misc\ShowCase.cs" />
diff --git a/ClosedXML/ClosedXML/ClosedXML_Examples/Creating/CreateFiles.cs b/ClosedXML/ClosedXML/ClosedXML_Examples/Creating/CreateFiles.cs
index 97d387f..c86f49d 100644
--- a/ClosedXML/ClosedXML/ClosedXML_Examples/Creating/CreateFiles.cs
+++ b/ClosedXML/ClosedXML/ClosedXML_Examples/Creating/CreateFiles.cs
@@ -65,6 +65,7 @@
             new FreezePanes().Create(@"C:\Excel Files\Created\FreezePanes.xlsx");
             new UsingTables().Create(@"C:\Excel Files\Created\UsingTables.xlsx");
             new ShowCase().Create(@"C:\Excel Files\Created\ShowCase.xlsx");
+            new CopyingWorksheets().Create();
         }
     }
 }
diff --git a/ClosedXML/ClosedXML/ClosedXML_Examples/Misc/CopyingWorksheets.cs b/ClosedXML/ClosedXML/ClosedXML_Examples/Misc/CopyingWorksheets.cs
new file mode 100644
index 0000000..10767ae
--- /dev/null
+++ b/ClosedXML/ClosedXML/ClosedXML_Examples/Misc/CopyingWorksheets.cs
@@ -0,0 +1,70 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using ClosedXML.Excel;
+
+using System.Drawing;
+
+namespace ClosedXML_Examples.Misc
+{
+    public class CopyingWorksheets
+    {
+        #region Variables
+
+        // Public
+
+        // Private
+
+
+        #endregion
+
+        #region Properties
+
+        // Public
+
+        // Private
+
+        // Override
+
+
+        #endregion
+
+        #region Events
+
+        // Public
+
+        // Private
+
+        // Override
+
+
+        #endregion
+
+        #region Methods
+
+        // Public
+        public void Create()
+        {
+            var wb = new XLWorkbook(@"C:\Excel Files\Created\BasicTable.xlsx");
+            var wsSource = wb.Worksheet(0);
+            // Copy the worksheet to a new sheet in this workbook
+            wsSource.CopyTo("Copy");
+
+            // We're going to open another workbook to show that you can
+            // copy a sheet from one workbook to another:
+            var wbSource = new XLWorkbook(@"C:\Excel Files\Created\BasicTable.xlsx");
+            wbSource.Worksheet(0).CopyTo(wb, "Copy From Other");
+
+            // Save the workbook with the 2 copies
+            wb.SaveAs(@"C:\Excel Files\Created\CopyingWorksheets.xlsx");
+        }
+
+        // Private
+
+        // Override
+
+
+        #endregion
+    }
+}
diff --git a/ClosedXML/ClosedXML/ClosedXML_Sandbox/Program.cs b/ClosedXML/ClosedXML/ClosedXML_Sandbox/Program.cs
index 9249434..4bf5333 100644
--- a/ClosedXML/ClosedXML/ClosedXML_Sandbox/Program.cs
+++ b/ClosedXML/ClosedXML/ClosedXML_Sandbox/Program.cs
@@ -12,14 +12,19 @@
 {
     class Program
     {
-        static void Main(string[] args)
+        static void xMain(string[] args)
         {
-            var wb = new XLWorkbook(@"C:\Excel Files\ForTesting\Blank_Modified.xlsx");
-            wb.SaveAs(@"C:\Excel Files\ForTesting\Blank_Modified2.xlsx");
-            //var l = new List<String>();
+            //var workbook = new XLWorkbook(@"C:\Excel Files\Created\BasicTable.xlsx");
+            var wb = new XLWorkbook(@"C:\Excel Files\ForTesting\Issue_6107.xlsx");
+            
 
-            //for (Int32 i = 1; i <= 10; i++)
-            //    ClosedXML_Examples.Program.ExecuteMain();
+            var templateWorksheet = wb.Worksheets.Where(w => w.Name == "TEMPLATE").FirstOrDefault();
+            var agentWorksheet = wb.Worksheets.Add("new");
+
+            agentWorksheet.FirstCell().Value = templateWorksheet.Range(templateWorksheet.FirstCellUsed(),
+                                                                       templateWorksheet.LastCellUsed());
+
+            wb.SaveAs(@"C:\Excel Files\ForTesting\Issue_6107_Saved.xlsx");
         }
         static void Main_5961(string[] args)
         {
@@ -46,15 +51,16 @@
             wb.Save();
         }
 
-        static void xMain(string[] args)
+        static void Main(string[] args)
         {
             FillStyles();
             List<Double> runningSave = new List<Double>();
             List<Double> runningLoad = new List<Double>();
             List<Double> runningSavedBack = new List<Double>();
-            var wb = new XLWorkbook();
+            
             foreach (Int32 r in Enumerable.Range(1, 5))
             {
+                var wb = new XLWorkbook();
                 var startTotal = DateTime.Now;
                 foreach (var i in Enumerable.Range(1, 1))
                 {