On Help Systems In General
http://www.mvps.org/htmlhelpcenter/htmlhelp/pdfs/onhelp.pdf

Liske, David E.
MVPs.org
2003

Abstract:

In the eras of Windows 3.x and earlier versions of Windows 95, the only help system people worked with or even knew about was WinHelp. Problems started with the transition to Windows 95, when developers and users alike had to learn to deal with WinHelp 4.0's separate dialog with the Contents, Index, and Find tabs.