1. Braun, S., Schwind, C.: Automatic, Semantics-based Indexing of Natural Language Texts for Information Retrieval Systems. (Technische Universität München, Report Nr. 7505 (1975)).
2. BROSS, I.D.J., PRIORE, R.L., SHAPIRO, P.A., STERMOLE, D.E., ANDERSON, B.B.: Feasibility of Automated Information Systems in the User’s Natural Language. Americ. Scientist 57 (1969) 193 – 205.
3. COLLEGE OF AMERICAN PATHOLOGISTS: Systematized Nomenclature of Medicine. (Chicago, Ill.: College of American Pathologists 1976).
4. GORDON, B.L. (ed.): Current Medical Information and Terminology (CMIT). (Chicago, Ill.: Medic. Ass. 1971).
5. HARRIS, Z.S.: Mathematical Structure of Language. (New York: Wiley 1968).