Rob Bovey, president of Application Professionals, specializes in MS Office, VB, and SQL Server application development. He developed several Excel add-ins shipped by Microsoft, and co-authored the Microsoft Excel 97 Developers Kit and Excel 2007 VBA Programmer's Reference. Stephen Bullen, co-author of The Excel 2007 VBA Programmer's Reference, owns Office Automation, Ltd. Dennis Wallentin, has developed Excel solutions since the 1980s through his firm, XL-Dennis. John Green (Sydney, Australia) owns Execuplan Consulting, which specializing in Excel and Access development. All four are Microsoft MVPs.