@article{IVM_1979_7_a3,
     author = {\`E. A. Golubov and M. V. Sapir},
     title = {Ideal extensions and commutative bundles of finitely approximable semigroups},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {22--30},
     year = {1979},
     number = {7},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1979_7_a3/}
}