Bisimulations and Boolean Vectors.
Tableaus for many-valued modal logic. Studia Logica , 55:63--87, 1995.
Kleene's three-valued logics and their children. Fundamenta Informaticae , 20:113--131, 1994.
Many-valued modal logics, II. Fundamenta Informaticae , 17:55--73, 1992.
Many-valued modal logics. Fundamenta Informaticae , 15:235--254, 1991.
Kleene's logic, generalized. Journal of Logic and Computation , 1:797--810, 1992.