http://doi.acm.org/10.1145/984514.984518 db/journals/sigmod/AuweraB82.html Yves Vander Auwera Luc Bernard New Proposal for a Common Command Language in Information Systems. 51-78 sigmodR/13-1/P051.pdf 1982 13 SIGMOD Record 1 db/journals/sigmod/sigmod13.html#AuweraB82