1. O. Yu. Shmidt, ?Groups whose subgroups are all special,? Matem. sb.,31, 366?372 (1924).
2. M. Suzuki, ?The nonexistence of a certain type of simple groups of odd order,? Proc. Am. Math. Soc.,8, No. 4, 686?695 (1957).
3. Z. Yanko, ?Endliche Gruppen mit lauter nilpotenten zweitmaximalen Untergruppen,? Math. Z.,79, 422?424 (1962).
4. S. A. Chunikhin, ?The existence of subgroups in finite groups,? Proceedings of a Seminar on Group Theory [in Russian], Moscow-Leningrad (1938), pp. 106?125.
5. Yu. A. Gol'fand, ?Groups whose subgroups are special,? Dokl. AN SSSR,60, No. 8, 1313?1315 (1948).