This material is made available in Adobe Acrobat (PDF) format and requires the Acrobat plug-in. If you don't use WordPerfect, you may not have the WPMathA fonts used in some of the PDF documents provided above (which may result in various equations being unreadable). You can install the needed fonts from Corel by going to http://www.corel.com/6763/downloads/WordPerfect/wpwin/9/wpfonts.exe, which should solve the problem.