1. Aceto, L., Fábregas, I., de Frutos-Escrig, D., Ingólfsdóttir, A., Palomino, M.: Graphical representation of covariant-contravariant modal formulae. In: EXPRESS, pp. 1–15 (2011)
2. Lecture Notes in Computer Science;R. Alur,1998
3. Antonik, A., Huth, M., Guldstrand Larsen, K., Nyman, U., Wasowski, A.: 20 years of modal and mixed specifications. Bulletin of the EATCS 95, 94–129 (2008)
4. Beneš, N., Černá, I., Křetínský, J.: Disjunctive modal transition systems and generalized LTL model checking. Technical report FIMU-RS-2010-12, Faculty of Informatics, Masaryk University, Brno (2010)
5. Lecture Notes in Computer Science;N. Beneš,2011