@InProceedings{AM+01,
    Author       = "Alechina, N. and Mendler, M. and de Paiva, V. and
                    Ritter, E.",
    Year         = "2001",
    Title        = "{Categorical and Kripke Semantics for Constructive S4 Modal
                    Logic}",
    Editor       = "Fribourg, L.",
    BookTitle    = "{Proceedings of the 15th International Workshop on Computer
                    Science Logic}",
    Place        = "Paris, France",
    Series       = "Lecture Notes in Computer Science",
    Number       = "2142",
    Pages        = "292-307",
    Publisher    = "Springer-Verlag",
    Comment      = "TPTPRef"
}