The Future of the User's Guide in the Documentation Set
http://www.stc.org/confproceed/1994/PDFs/PG104106.PDF

Farkas, David K.
STC Proceedings
1994

Abstract:

With online help rapidly becoming the central piece in the documentation set, software companies might consider two different directions in their documentation planning. The first is to think of the user’s guide as a high-quality supplement to help. The second is to think of the user's guide as a transitional piece that will adequately support users while they make the transition to a largely online documentation set. Each of these directions carries different implications for the design of the user’s guide.