Books on UserForms

I am in the process of learning how to create UserForms and Dialog Boxes in Excel 97. I have Purchased Excel 97 Programming for Windows for Dummies, and Microsoft Excel 97 Visual Basic Step by Step. Although the books have helped me learn some of the Basics, they only seem to cover a small portion of
information on UserForms and Dialog Boxes. I was wondering if you can recomend any books that might cover Userforms & Dialog Boxes in more detail?

Thanks in Advance
Paul Magruder