中国科学院数学与系统科学研究院期刊网
AMS
Maximal and Minimal Congruences on Some Semigroups
Jintana SANWONG, Boorapa SINGHA, R.P.SULLIVAN
Acta Mathematica Sinica . 2009, (3): 455 -466 .  DOI: 10.1007/s10114-008-6280-7