1. Almeida, J.: Finite Semigroups and Universal Algebra. World Scientific, Singapore (1994)
2. Baldwin, J., Berman, J.: Varieties and finite closure conditions. Colloq. Math. 35, 15–20 (1976)
3. Carton, O., Pin, J.-E., Soler-Escrivà, X.: Languages recognized by finite supersoluble groups (submitted)
4. Eilenberg, S.: Automata, Languages and Machines, vol. A,B. Academic Press, New York (1974-1976)
5. Lecture Notes in Computer Science;Z. Ésik,2003