1. Infinite Abelian Groups, vol. II;Fuchs,1973
2. On some questions in the theory of nilpotent and locally nilpotent groups without torsion;Glus̆kov;Mat. Sb.,1952
3. Powerful p-groups I. Finite groups;Lubotzky;J. Algebra,1987
4. A Course in the Theory of Groups;Robinson,1982
5. Finiteness Conditions and Generalized Soluble Groups, vols. 1 and 2;Robinson,1972