1. Bourbaki, Topologie Generale. Ch. I, Paris 1961.
2. J.Dixon, Problems in Group Theory. New York 1973.
3. B.Huppert, Endliche Gruppen. Vol. 1, Berlin-Heidelberg-New York 1967.
4. O. H.Kegel and B. A. F.Wehrfritz, Locally Finite Groups. New York 1973.
5. D.Passman, Permutation Groups. New York-Amsterdam 1968.