1. T. R. Berger, Hall-Higman type theorems II, Trans. Amer. Math. Soc., to appear.
2. Group Representation Theory;Dornhoff,1972
3. Endliche Gruppen I;Huppert,1967
4. I. M. Isaacs, Character degrees and derived length of a solvable group, to appear.
5. Permutation Groups;Passman,1968