F. Neven, and J. den Bussche. PODS '98. Proceedings of the seventeenth ACM SIGACT-SIGMOD-SIGART
symposium on Principles of database systems, page 11--17. ACM press, (1998)
L. Fegaras, D. Maier, and T. Sheard.. Third International Conference on Deductive and Object-Oriented Databases, page 146--168. Phoenix, Arizona, (December 1993)
W. Plath. 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)..