@article{GDZPPN00126270X,
title = {The a-congruences on S(X) and the S-equivalences on X.},
journal = {Semigroup forum},
volume = {46},
year = {1993},
pages = {48-59},
zbl = {0784.20034},
url = {http://dml.mathdoc.fr/item/GDZPPN00126270X}
}
Pei, H. The a-congruences on S(X) and the S-equivalences on X.. Semigroup forum, Tome 46 (1993) pp. 48-59. http://gdmltest.u-ga.fr/item/GDZPPN00126270X/