The Role of Indexing in Technical Communication
http://www.stcboston.org/archives/articles/indexing.shtml

Northrop, Mary Jane
Boston Broadside
1993

Abstract:

The success of a technical document depends heavily on the index. The task of indexing a technical document often cannot begin until insufficient time remains to do a good job. However, for many users of the document, a good index is mandatory to its usability.