An SQL-Based Query Language For Networks of Relations.

http://doi.acm.org/10.1145/382274.382910 db/journals/sigmod/BasuA90.html Amit Basu Rafiul Ahad An SQL-Based Query Language For Networks of Relations. 8-17 sigmodR/19-1/P008.pdf 1990 19 SIGMOD Record 1 db/journals/sigmod/sigmod19.html#BasuA90