@article {ART-1989-01,
    author = {Frank Leymann},
    title = {{A Survey of the Universal Relation Model}},
    journal = {Data \& Knowledge Engineering},
    publisher = {Elsevier},
    volume = {4},
    number = {4},
    pages = {305--320},
    type = {Article in Journal},
    month = {January},
    year = {1989},
    language = {English},
    cr-category = {H.4.2 Information Systems Applications Types of Systems},
    department = {University of Stuttgart, Institute of Architecture of Application Systems},
    abstract = {A Survey of the Universal Relation Model},
    url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=ART-1989-01&engl=1}
 }