[1] A. H. Clifford, G. В. Preston: The Algebraic Theory of Semigroups, Vol. 1. Amer. Math. Soc, Math. Surveys No. 7, 1961. MR 0132791

[2] Maurice Crestey: Applications multiformes partielles. Collectanea Mathematica, Univ. of Barcelona 16 (1964), 111-126 (Math. Rev. 34, 262). MR 0200366

[3] L. M. Gluskin: Ideals of semigroups of transformations. (Russian), Mat. Sb. (N.S.) 47 (1959), 111-130 (Math. Rev. 21, 4197). MR 0105456 | Zbl 0084.02703

[4] L. M. Gluskin: Automorphisms of semigroups of binary relations. (Russian), Ural. Gos. Univ. Mat. Zap. 6, tetrad' 1, 44-54 (1967) (Math. Rev. 36, 1560). MR 0218474

[5] E. S. Ljapin: Semigroups. Moscow 1960; Amer. Math. Soc. Translation, 1963. MR 0167545

[6] Kenneth D. Magill, Jr.: Automorphisms of the semigroup of all relations on a set. Canad. Math. Bull. 9 (1966), 73-77 (Math. Rev. 34, 263). DOI 10.4153/CMB-1966-009-7 | MR 0200367

[7] A. I. Malcev: Symmetric groupoids. (Russian), Mat. Sb. (N.S.) 31 (1952), 136-151 (Math. Rev. 14, 349). MR 0050576

[8] I. Schreier: Über Abbildungen einer abstrakten Menge auf ihre Teilmenge. Fund. Math. 28 (1937), 261-264.

[9] K. A. Zareckii: The semigroup of completely effective binary relations. (Russian), Theory of Semigroups and Applications I (Russian), pp. 238-250, Izdat. Saratov. Univ., Saratov, 1965. MR 0193162