1. Report on the Testing and Analysis of an Investigation into the Comparative Efficiency of Indexing Systems, Cranfield, England: College of Aeronautics, ASLIB Cranfield Research Project, October 1962.
2. The Effect of Indexing Specificity on Retrieval Performance, Doctoral dissertation, Graduate Library School, University of Chicago, 1971.
3. Subject Headings: The History and Theory of the Alphabetical Subject Approach to Books, New York: H. W. Wilson, 1946, p. 81.
4. Computer Evaluation of Indexing and Text Processing
5. What makes an automatic keyword classification effective?