- Bericht, TUM-INFO-7710. Institut für Informatik, Tech. University München, (May 1977)
- Information Processing Letters 14(3):132--138 (May 1982)
- report RC, 4396. IBM T.J. Watson Research Center, Yorktown Heights, NY, (May 1973)
- International Business Machines Corporation. Journal of Research and Development 20(4):326--335 (July 1976)See also: report RC 5604, IBM T.J. Watson Research Center, Yorktown Heights, NY August 1975. .
- Computational and Mathematical Linguistics~II, Leo S. Olschki Editore, Firenze, (1977)
- International Journal of Computer and Information Sciences 13(6):425--460 (1984)
- BIT (1984)
- report, A-1987-5. Department of Comp. Sc., University of Tampere, (March 1987)
- PODS '98. Proceedings of the seventeenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems, page 11--17. ACM press, (1998)
- 8th Int. Joint Conf. on Artificial Intelligence, Karlsruhe, (August 1983)
- ACM Computer Science Conf., ACM press, (March 1985)
- CS-94-05. Department of Computer Science, Brown University, (February 1994)
- report, A7. Department of Comp. Sc., University of Tampere, (August 1974)
- 2nd ACM Symp. on Principles of Database Systems, ACM press, (March 1983)
- Technischen Universit�t Braunschweig, (1991)
- 9th ACM Symp. on Principles of Progr. Languages, ACM press, Albuquerque, NM, (January 1982)
- Third International Conference on Deductive and Object-Oriented Databases, page 146--168. Phoenix, Arizona, (December 1993)
- Information Systems 14(6):507--514 (1989)


user