“Understanding the Excel Object Model from a .NET Developer's Perspective”:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/odc_vsto2003_ta/html/ExcelObj.asp
“Automating Excel Using the Excel Object Model”:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dv_wrcore/html/wroriautomatingexcelusingexcelobjectmodel.asp