[1] Clifford A H, Preston G B. The Algebrac Theorey of Semigroups. Vol I & Vol II. Providence RI: Amer Math Soc, 1961 & 1967

[2] Fountain J B. Right PP monoid with central idempotents. Semigroup Forum, 1977, 13: 229–237

[3] Fountain J B. Abundant semigroups. Proc London Math Soc, 1982, 44(3): 103–129

[4] Guo Y Q, Shum K P, Zhu P Y. The structure of left C-rpp semigroups. Semigroup Forum, 1995, 50: 9–23

[5] Guo Y Q. The right dual of left C-rpp semigroups. Chinese Science Bulletin, 1997, 42(19): 1599–1602

[6] Guo X J, Shum K P, Guo Y Q. Perfect C-rpp semigroups. Comm Alg, 2001, 29(6): 2447–2459

[7] Howie J M. Fundamentals of Semigroup Theory. Oxford: Oxford Science Publications, 1995

[8] Pastijn F. A representation of a semigroup by a semigroup of matrices over a group with zero. Semigroup Forum, 1975, 10: 238–249

[9] Petrich M, Reilly N R. Completely Regular Semigroups. New York: Wiley-Interscience Publication, 1999

[10] Shum K P, Guo X J, Ren X M. (l)-Green’s relations and perfect semigroups//Proceedings of AMC 2000, Manila. Singapore: World Scientific Inc, 2002: 604–613