John Walkenbach

John Walkenbach, a.k.a. Mr. Spreadsheet, is arguably the foremost authority on Excel. His forty-plus books include Excel "2007 Power Programming with VBA," "Excel 2007 Formulas," and the bestselling "Excel 2007 Bible," all published by Wiley. He has also written hundreds of articles and created the award-winning Power Utility Pak. Visit John's popular Spreadsheet Page at