[1] CLIFFORD A. H., PRESTON G. B.: The algebraic theoгy of semigroup. Mat. Surveys of the American Math. Soc. 7, A.M.S Pгovidence R.I., Vol. I 1961, Vol. II 1967.

[2] DELANY J. E.: Tensor product of semilattices. Portugaliae Mathematica 31, 1972, 193-202 MR 0306063 | Zbl 0251.06013

[3] FULP R.: Tensor and torsion products of semigroups. Pacif. J. of Math. 32, 1970, 685-696. MR 0272928 | Zbl 0223.20080

[4] GRILLET P. A.: The tensoг product of semigroups. Trans. Amer. Math. Soc. 138, 1969, 267-280. MR 0237687

[5] GRILLET P. A.: The tensor product of commutative semigroups. Trans. Amer. Math. Soc. 138, 1969, 281-293. MR 0237688 | Zbl 0191.01602

[6] HEAD T. J.: Homomoгphisms of commutative semigroups as tensor maps. J. Nat. Sci. and Math. 7, 1967, 39-49. MR 0230828

[7] KIMURA N.: Tensor product of semilattices. Notices Ameг. Math. Soc 17, 1970, 554.

[8] SATKO L.: Tenzorové súčiny pologrúp a gгupoidov. Kandidátska dizеrtačná pгáca. Bгatislava, apríl 1977.

[9] TAMURA T.: Maximal oг grеatеst homomorphic imagеs of givеn typе. Canad J. Math 20 (2), 1968, 264-271. MR 0228613