Agafontseva Mladena Vladimirovna, Chekhlov Andrey Rostislavovich «On abelian groups with central squares of commutators of endomorphisms» // 2013. №4(24) C.54-59
Chekhlov Andrey Rostislavovich «E-engelian abelian groups of step ≤ 2» // 2012. №1(17) C.54-60
