1. J. H.Conway, Three lectures on exceptional groups. In: Finite Simple Groups (ed. M. B.Powell, G.Higman), p. 215?247, New York 1971.
2. L. Finkelstein, Finite groups with a standard component of typeJ 4. Pacific J. Math.71, 41?55 (1977).
3. W. Gasch�tz, Zur Erweiterungstheorie endlicher Gruppen. J. reine angew. Math.190, 93?107 (1952).
4. D.Gorenstein, Finite Groups. New York 1968.
5. B.Huppert, Endliche Gruppen I. Berlin-Heidelberg-New York 1967.