@article{IVM_1969_2_a7,
     author = {I. S. Ponizovskii},
     title = {Congruences on semigroups},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {72--78},
     publisher = {mathdoc},
     number = {2},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1969_2_a7/}
}