@article{GDZPPN001254138,
title = {A new notion in the theory of semigroups.},
journal = {Semigroup forum},
volume = {20},
year = {1980},
pages = {233-240},
zbl = {0439.20045},
url = {http://dml.mathdoc.fr/item/GDZPPN001254138}
}
Satko, L.; Grosek, O. A new notion in the theory of semigroups.. Semigroup forum, Tome 20 (1980) pp. 233-240. http://gdmltest.u-ga.fr/item/GDZPPN001254138/