1. Information Retrieval and the Computer. London: Macdonald and Jones; 1977: 33.
2. U.S. Department of Health, Education, and Welfare. The Principles of MEDLARS. Washington, DC: U.S. GPO; 1969.
3. Aslib Cranfield Research Project. Cranfield: Aslib; 1962: 84.
4. Medline: An introduction to on-line searching
5. The Automatic Creation of Literature Abstracts