1. Über das Produkt von zwei abelschen Gruppen;Itô, Noboru;Math. Z.,1955
2. A remark on the general product of two infinite cyclic groups;Cohn, P. M.;Arch. Math. (Basel),1956
3. The product of finitely connected abelian groups;Sesekin, N. F.;Sibirsk. Mat. \v{Z}.,1968
4. The general product of two finitely generated abelian groups;Schenkman, Eugene;Proc. Amer. Math. Soc.,1969
5. W. R. Scott, On a result of Schenkman on products of abelian groups, Notices Amer. Math. Soc. 16 (1969), 796. Abstract #667-137.