@inproceedings{
    Niemela91:ijcai,
    author = {Niemel{\"a}, Ilkka},
    publisher = "Morgan Kaufmann Publishers",
    title = "Constructive Tightly Grounded Autoepistemic Reasoning",
    booktitle = "Proceedings of the 12th International Joint Conference on Artificial Intelligence",
    address = "Sydney, Australia",
    month = "August",
    year = "1991",
    organization = "",
    pages = "399--404"
}