@unpublished{
    Niemela92:psnmr,
    author = {Niemel{\"a}, Ilkka},
    note = {Lecture Notes of the Summer School on Partial Semantics and Non-Monotonic Reasoning (Link\"oping, Sweden, May 25--29, 1992)},
    year = "1992",
    title = "Autoepistemic Logic as a Basis for Automating Nonmonotonic Reasoning"
}