1. Chernikov, N. S.: Groups which are Products of Permutable Subgroups, Nauk. Dumka, Kiev, 1987, 206 p. (in Russian).
2. Chernikov, N. S.: Groups which are factorized by pairwise permutable periodic subgroups without elements of the same prime ordes, In: Investigations of Groups with Restrictions for Subgroups, In-t Math. NAS Ukraine, Kiev, 1988, pp. 98?117 (in Russian).
3. Chernikov, N. S.: Factorization of linear groups and groups possessing a normal system with linear factors, Ukrain. Math. J. 40(3) (1988), 362?369.
4. Chernikov, N. S.: The solavibility and the locally solvability of factorized RN-groups, In: Methods of Investigation of Algebraic and Topological Structures, Pedagogical Institute, Kiev, 1989, pp. 122?129 (in Russian).
5. Chernikov, N. S.: Factorization of groups by periodic permutable subgroups without elements of the same prime orders, Ukrain. Math. J. 43(10) (1991), 1429?1436.