@article{IVM_1988_7_a12,
     author = {A. B. Ugol'nikov},
     title = {Closed {Post} classes},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {79--88},
     publisher = {mathdoc},
     number = {7},
     year = {1988},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1988_7_a12/}
}