Factor-splitting Abelian groups of arbitrary rank Ladislav Bican (1978) Commentationes Mathematicae Universitatis Carolinae
Finite Groups of Exponent 12 as Automorphism Groups. Kurt A. Hirsch, J. Terry Hallett (1977) Mathematische Zeitschrift
Free subgroups in the endomorphism ring of an Abelian free group Haimo, Franklin (1981) Portugaliae mathematica