1. V. V. Vagner, “Generalized groups,” Dokl. Akad. Nauk SSSR, 84, No. 6, 1119–1122 (1952).
2. A. H. Clifford and G. B. Preston, The Algebraic Theory of Semigroups, Amer. Math. Soc., Providence, RI, Vol. 1 (1961); Vol. 2 (1972).
3. O. Gutik and I. Pozdnyakova, “On monoids of monotone injective partial self-maps of L n × lexℤ with cofinite domains and images,” Algebra Discr. Math., 17, No. 2, 256–279 (2014).
4. O. Gutik and D. Repovš, “On monoids of injective partial self-maps of integers with cofinite domains and images,” Georgian Math. J., 19, No. 3, 511–532 (2012).
5. O. Gutik and D. Repovš, “Topological monoids of monotone, injective partial self-maps of ℕ having cofinite domain and image,” Stud. Sci. Math. Hungar., 48, No. 3, 342–353 (2011).