diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/Comments/XLComment.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/Comments/XLComment.cs
index b93319f..83f5846 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/Comments/XLComment.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/Comments/XLComment.cs
@@ -155,7 +155,7 @@
 
         private void Initialize(XLCell cell)
         {
-            Author = Environment.UserName;
+            Author = cell.Worksheet.Author;
             Container = this;
             Anchor = XLDrawingAnchor.MoveAndSizeWithCells;
             Style = new XLDrawingStyle();
diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/IXLWorksheet.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/IXLWorksheet.cs
index 6350bba..0d9dcd6 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/IXLWorksheet.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/IXLWorksheet.cs
@@ -367,5 +367,6 @@
 
         Object Evaluate(String expression);
 
+        String Author { get; set; }
     }
 }
diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook.cs
index d9e8791..e005b74 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook.cs
@@ -552,7 +552,7 @@
             NamedRanges = new XLNamedRanges(this);
             CustomProperties = new XLCustomProperties(this);
             ShapeIdManager = new XLIdManager();
-
+            Author = Environment.UserName;
         }
 
         /// <summary>
@@ -696,5 +696,7 @@
         {
             return CalcEngineExpr.Evaluate(expression);
         }
+
+        public String Author { get; set; }
     }
 }
\ No newline at end of file
diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Load.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Load.cs
index dcc5714..effcba6 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Load.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Load.cs
@@ -866,7 +866,8 @@
             else if (cell.CellValue != null)
             {
                 var numberFormatId = ((CellFormat) (s.CellFormats).ElementAt(styleIndex)).NumberFormatId;
-                xlCell._cellValue = Double.Parse(cell.CellValue.Text, CultureInfo.InvariantCulture).ToString();
+                if (!XLHelper.IsNullOrWhiteSpace(cell.CellValue.Text))
+                    xlCell._cellValue = Double.Parse(cell.CellValue.Text, CultureInfo.InvariantCulture).ToString();
                 if (s.NumberingFormats != null &&
                     s.NumberingFormats.Any(nf => ((NumberingFormat) nf).NumberFormatId.Value == numberFormatId))
                 {
diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Save.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Save.cs
index f6ebc55..5e08e24 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Save.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Save.cs
@@ -4129,7 +4129,8 @@
                         }
                         else if (dataType == XLCellValues.DateTime || dataType == XLCellValues.Number)
                         {
-                            cellValue.Text = Double.Parse(opCell.InnerText).ToString(CultureInfo.InvariantCulture);
+                            if (!XLHelper.IsNullOrWhiteSpace(opCell.InnerText))
+                                cellValue.Text = Double.Parse(opCell.InnerText).ToString(CultureInfo.InvariantCulture);
                             cell.CellValue = cellValue;
                         }
                         else
diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorksheet.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorksheet.cs
index fbf3684..c7137d9 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorksheet.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorksheet.cs
@@ -82,6 +82,8 @@
             RightToLeft = workbook.RightToLeft;
             TabColor = new XLColor();
             SelectedRanges = new XLRanges();
+
+            Author = workbook.Author;
         }
 
         #endregion
@@ -1431,5 +1433,7 @@
         {
             return CalcEngine.Evaluate(expression);
         }
+
+        public String Author { get; set; }
     }
 }
\ No newline at end of file
diff --git a/ClosedXML/ClosedXML/ClosedXML_Examples/Comments/AddingComments.cs b/ClosedXML/ClosedXML/ClosedXML_Examples/Comments/AddingComments.cs
index dba1b3f..fe5b0d3 100644
--- a/ClosedXML/ClosedXML/ClosedXML_Examples/Comments/AddingComments.cs
+++ b/ClosedXML/ClosedXML/ClosedXML_Examples/Comments/AddingComments.cs
@@ -10,9 +10,9 @@
     public class AddingComments : IXLExample 
     {
 
-        public void Create(string filePath) 
+        public void Create(string filePath)
         {
-            var wb = new XLWorkbook();
+            var wb = new XLWorkbook {Author = "Manuel"};
             AddMiscComments(wb);
             AddVisibilityComments(wb);
             AddPosition(wb);