Quality and Usability in Indexes
http://www.stc.org/confproceed/1997/PDFs/0124.PDF

Lathrop, Lori M., Peg Mauer and L. Pilar Wyman
STC Proceedings
1997

Abstract:

Indexes are essentially user interfaces for product documentation and trade books. Determining the quality and usability of indexes requires many of the same considerations as determining the quality and usability of user interfaces for software products. The time and resources spent on indexing represent the most cost-effective investments companies and publishers can make. Unfortunately, the truth is that very few companies and publishers devote a sufficient amount of time and resources to developing indexes.