conf/vldb/81 C. J. Date Referential Integrity VLDB81/P002.PDF 2-12 1981 VLDB db/conf/vldb/vldb81.html#Date81 db/conf/vldb/Date81.html ... journals/cacm/Codd70 journals/tods/Codd79 conf/sigmod/CoddD74 ... conf/vldb/Date80 ... conf/vldb/EswaranC75 ... ... ...