[2] A. Cherubini Spoletini and A. Varisco:
Quasi commutative semigroups and $\sigma $-reflexive semigroups. Semigroup Forum 19 (1980), 313–321.
DOI 10.1007/BF02572524 |
MR 0569810
[3] A. Cherubini Spoletini and A. Varisco:
Quasi hamoltoniam semigroups. Czechoslovak Math. J. 33(108) (1983), 131–140.
MR 0687426
[4] Z. L. Gao and K. P. Shum:
On cyclic commutative po-semigroups. PU.M.A. 18 (1997), 261–273.
MR 1630495
[6] N. P. Mukherjee:
Quasi commutative semigroups I. Czechoslovak Math. J. 22(97) (1972), 449–453.
MR 0308301
[9] B. Pondělíček:
On weakly commutative semigroups. Czechoslovak. Math. J. 25(100) (1975), 20–23.
MR 0387460
[11] K. P. Shum, X. M. Ren and Y. Q. Guo:
On Quasi-Left Groups. Groups-Korea’94, Walter de Gruyter & Co., Berlin, New York, 1995, pp. 285–288.
MR 1476972
[12] K. P. Shum and Y. Q. Guo:
Regular semigroups and its generalizations. Lecture Series 181 (Pure & Applied Math.), Marcell Dekker INC., 1996, pp. 181–225.
MR 1408694