@article{GDZPPN001255533, title = {Identities valid globally in semigroups.}, journal = {Semigroup forum}, volume = {24}, year = {1982}, pages = {263-270}, url = {http://dml.mathdoc.fr/item/GDZPPN001255533} }
Ljapin, E.D. Identities valid globally in semigroups.. Semigroup forum, Tome 24 (1982) pp. 263-270. http://gdmltest.u-ga.fr/item/GDZPPN001255533/