[MSDN Library June 1998] Calculating the Size of a 9,000,000 Row Table with a Nonclustered Index (17.9946361213967%)
MSDN Library Visual Studio 6.0 > Platform SDK > Database and Messaging Services > Microsoft SQL Server Programmer's Toolkit > Administrator's Companion > Appendix B Estimating Database Size > Calculating the Size of a Nonclustered Index