OlaO89'

@inproceedings{DBLP:conf/vldb/OlaO89,
  author    = {Adegbemiga Ola and
               Gultekin {\"O}zsoyoglu},
  title     = {A Family of Incomplete Relational Database Models},
  booktitle = {VLDB},
  year      = {1989},
  pages     = {23-31},
  ee        = {http://www.vldb.org/conf/1989/P023.PDF},
  crossref  = {DBLP:conf/vldb/89},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}

@proceedings{DBLP:conf/vldb/89,
  editor    = {Peter M. G. Apers and
               Gio Wiederhold},
  title     = {Proceedings of the Fifteenth International Conference on
               Very Large Data Bases, August 22-25, 1989, Amsterdam, The
               Netherlands},
  publisher = {Morgan Kaufmann},
  year      = {1989},
  isbn      = {1-55860-101-5},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}