REFERENCES
- Adjan , S. I. ( 1978 ). The Burnside Problem and Identities in Groups . Berlin : Springer Verlag .
- Baer , R. ( 1953 ). Factorization of n-soluble and n-nilpotent groups . Proc. Amer. Math. Soc. 4 : 15 – 26 .
- Brandl , R. , Kappe , L.-C. ( 1989 ). On n-Bell groups . Comm. Algebra 17 ( 4 ): 787 – 807 .
- Delizia , C. , Moghaddam , M. R. R. , Rhemtulla , A. ( 2006 ). The structure of Bell groups . J. Group Theory 9 ( 1 ): 117 – 125 .
- Delizia , C. , Moravec , P. , Nicotera , C. Locally graded Bell groups . To appear in Publ. Math. Debrecen .
- Kappe , W. P. ( 1961 ). Die a-norm Einer gruppe . Illinois J. Math. 5 : 187 – 197 .
- Kappe , L.-C. ( 1986 ). On n-Levi groups . Arch. Math. 47 : 198 – 210 .
- Kappe , L.-C. , Morse , R. F. ( 1988 ). Groups with 3-abelian normal closure . Arch. Math. 51 ( 2 ): 104 – 110 .
- Levi , F. W. ( 1942 ). Groups in which the commutator operation satisfies certain algebraic conditions . J. Indian Math. Soc. 6 : 87 – 97 .
- Mihăilescu , P. ( 2004 ). Primary cyclotomic units and a proof of Catalan's conjecture . J. Reine Angew. Math. 572 : 167 – 195 .
- Moravec , P. ( 2006 ). On power endomorphisms of n-central groups . J. Group Theory 9 ( 4 ): 519 – 536 .
- Robinson , D. J. S. ( 1972 ). Finiteness Conditions and Generalized Soluble Groups . Part 1 and Part 2 . Berlin : Springer Verlag .
- Robinson , D. J. S. ( 1996 ). A Course in the Theory of Groups . \ed{2nd ed}. New York : Springer Verlag .
- Smith , H. ( 1994 ). On homomorphic images of locally graded groups . Rend. Sem. Mat. Univ. Padova 91 : 53 – 60 .
- Communicated by M. R. Dixon.