1. Finite Rank Torsion Free Abelian Groups and Rings VIII;Arnold,1982
2. Torsion-Free Groups of Rank Two;Beaumont,1961
3. Automorphisms of Torsion-Free Abelian Groups;Bekker,1988
4. Set Theoretic Methods in Homological Algebra and Abelian Groups;Eklof,1980
5. Additive Groups of Rings;Feigelstock,1983