1. Alternation;Chandra;Journal of the ACM,1981
2. Introduction to Lattices and Order;Davey,2002
3. Formal Concept Analysis: Mathematical Foundations;Ganter,1999
4. The effect of bounding the number of primitive propositions and the depth of nesting on the complexity of modal logic;Halpern;Artificial Intelligence,1995
5. C. Herrmann, P. Luksch, M. Skorsky, R. Wille, Algebras of semiconcepts and double Boolean algebras, Technische Universität Darmstadt, 2000.