@inproceedings{
    Niemela88:csl,
    author = {Niemel{\"a}, Ilkka},
    publisher = "Springer-Verlag",
    title = "On the Complexity of the Decision Problem in Propositional Nonmonotonic Logic",
    booktitle = "Proceedings of the 2nd Workshop on Computer Science Logic",
    address = "Duisburg, FRG",
    month = "October",
    year = "1988",
    pages = "226--239"
}