@article{SF_1974__6_133966,
     author = {V.V. Demencuk},
     title = {Semigroups of rank 1 (in {Russian).}},
     journal = {Semigroup forum},
     pages = {95--99},
     year = {1974},
     volume = {6},
     zbl = {0255.20041},
     url = {http://geodesic.mathdoc.fr/item/SF_1974__6_133966/}
}