@techreport{
    DFN98:tr,
    author = {Dix, J\"{u}rgen and Furbach, Ulrich and Niemel\"{a}, Ilkka},
    title = "Nonmonotonic {R}easoning: {T}owards {E}fficient {C}alculi and {I}mplementations",
    number = "20--98",
    month = "August",
    note = "Available at \url{http://www.uni-koblenz.de/fb4/publikationen/gelbereihe/}",
    year = "1998",
    type = "Fach\-be\-richt Informatik",
    institution = {Universit{\"a}t Koblenz-Landau}
}