@workingPaper{BuchheitJeusfeldNuttStaudt_1993,
title={Subsumption between queries to object-oriented databases},
author={Buchheit, Martin and Jeusfeld, Manfred A. and Nutt, Werner and Staudt, Martin},
doi={http://dx.doi.org/10.22028/D291-24928},
year={1993}
}