A note on pseudocongruences in semigroups
N. Kehayopulu, M. Tsingelis

References
1.	N. Kehayopulu and M. Tsingelis, “On subdirectly irreducible ordered semigroups”, Semigroup Forum, 50 (1995), 161–177
2.	Xie Xiang-Yun, “Fuzzy ideal extensions of semigroups”, Soochow J. Math., 27:2 (2001), 125–138