1. Aghdam A.M., Square subgroup of an Abelian group, Acta. Sci. Math. 51 (1987), 343–348.
2. Aghdam A.M., Rings on indecomposable torsion free groups of rank two, Int. Math. Forum 1 (2006), no. 3, 141–146.
3. Aghdam A.M., Najafizadeh A., Square subgroups of rank two Abelian groups, Colloq. Math. 117 (2009), no. 1, 19–28.
4. Aghdam A.M., Najafizadeh A., Square submodule of a module, Mediterr. J. Math. 7 (2010), no. 2, 195–207.
5. Aghdam A.M., Najafizadeh A., On the indecomposable torsion-free abelian groups of rank two, Rocky Mountain J. Math. 42 (2012), no. 2, 425–438.
6. Andruszkiewicz R.R., Woronowicz M., Some new results for the square subgroup of an abelian group, Comm. Algebra 44 (2016), no. 6, 2351–2361.
7. Andruszkiewicz R.R., Woronowicz M., A torsion-free abelian group exists whose quotient group modulo the square subgroup is not a nil-group, Bull. Aust. Math. Soc. 94 (2016), no. 3, 449–456.
8. Andruszkiewicz R.R., Woronowicz M., On additive groups of associative and commutative rings, Quaest. Math. 40 (2017), no. 4, 527–537.
9. Andruszkiewicz R.R., Woronowicz M., On the square subgroup of a mixed SI-group, Proc. Edinburgh Math. Soc. 61 (2018), no. 1, 295–304.
10. Beaumont R.A., Wisner R.J., Rings with additive group which is a torsion-free group of rank two, Acta. Sci. Math. Szeged 20 (1959), 105–116.
11. Feigelstock S., On the type set of groups and nilpotence, Comment. Math. Univ. St. Pauli 25 (1976), 159–165.
12. Feigelstock S., The absolute annihilator of an abelian group modulo a subgroup, Publ. Math. Debrecen 23 (1976), 221–224.
13. Feigelstock S., Additive groups of rings, Vol. 1, Pitman Advanced Publishing Program, Boston, 1983.
14. Fuchs L., Infinite abelian groups, Vol. 1, Academic Press, New York, London, 1970.
15. Fuchs L., Infinite abelian groups, Vol. 2, Academic Press, New York, 1973.
16. Hasani F., Karimi F., Najafizadeh A., Sadeghi M.Y., On the square subgroups of decomposable torsion-free abelian groups of rank three, Adv. Pure Appl. Math. 7 (2016), no. 4, 259–265.
17. Najafizadeh A., On the square submodule of a mixed module, Gen. Math. Notes 27 (2015), no. 1, 1–8.
18. Stratton A.E., Webb M.C., Abelian groups, nil modulo a subgroup, need not have nil quotient group, Publ. Math. Debrecen 27 (1980), 127–130.
19. Woronowicz M., A note on additive groups of some specific associative rings, Ann. Math. Sil. 30 (2016), 219–229.
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