Six Slick Tests for Docs and Help
http://www.uie.com/articles/documentation_help/

User Interface Engineering
1998

Abstract:

Usability testing isn’t just for software and web sites. Testing documentation can ensure that it includes — and accurately conveys — all the information users expect and need. Testing gives you accurate information on how well your documentation and Help work. It can even uncover problems that are better solved by changing the interface.