@techreport{
    NS:FB96NR7,
    author = {Niemel{\"a}, Ilkka and Simons, P.},
    title = "Efficient Implementation of the Well-founded and Stable Model Semantics",
    number = "7--96",
    note = "Available at \url{http://www.uni-koblenz.de/fb4/publikationen/gelbereihe/}",
    year = "1996",
    type = "Fach\-be\-richt Informatik",
    institution = {Universit{\"a}t Koblenz-Landau}
}