James Clifford Albert Croker The Historical Relational Data Model (HRDM) and Algebra Based on Lifespans. 528-537 ICDE87/P528.pdf 1987 ICDE db/conf/icde/icde87.html#CliffordC87 conf/icde/87 db/conf/icde/CliffordC87.html ... ... conf/popl/CasanovaB79 journals/tods/Chen76 ... journals/tods/CliffordW83 conf/sigmod/CliffordT85 conf/pods/GadiaV85 conf/er/Klopprogge81 conf/vldb/KlopproggeL83 conf/sigmod/LumDEGPWWW84 journals/tods/Navathe80 ... conf/pods/Snodgrass84 conf/sigmod/SnodgrassA85