1. V. A. Andrunakievich, Radicals of associtive rings II (Russian), Mat. Sb., 55 (1961), 329–346. English translation: Amer. Math. Soc. Transl., (2) 52 (1966), 129–150.
2. V. A. Andrunakievich and Yu. M. Ryabukhin, Modules and radicals (Russian), Dokl. Akad. Nauk SSSR, 156 (1964), 991–994. English translation: Soviet Math Dokl., 3 (1964), 728–732.
3. A. L. S. Corner, Every countable reduced torsion-free ring is an endomorphism ring, Proc. London Math. Soc., 13 (1963), 687–710.
4. S. E. Dickson, Torsion classes of abelian groups, J. Math. Soc. Japan, 17 (1965), 30–35.
5. M. Dugas and S. Feigelstock, Nil R-mod abelian groups, Math. Proc. Roy. Irish Acad., 102A (2002), 107–113.