Voir la notice de l'article provenant de la source Math-Net.Ru
@article{IVM_1972_3_a10, author = {V. A. Fortunatov}, title = {Perfect semigroups}, journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika}, pages = {80--89}, publisher = {mathdoc}, number = {3}, year = {1972}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/IVM_1972_3_a10/} }
V. A. Fortunatov. Perfect semigroups. Izvestiâ vysših učebnyh zavedenij. Matematika, no. 3 (1972), pp. 80-89. http://geodesic.mathdoc.fr/item/IVM_1972_3_a10/