@article{ZVMMF_1977_17_5_a18,
     author = {R. G. Nigmatullin},
     title = {The complexity of languages of type $\cup\mathrm M$},
     journal = {\v{Z}urnal vy\v{c}islitelʹnoj matematiki i matemati\v{c}eskoj fiziki},
     pages = {1278--1284},
     publisher = {mathdoc},
     volume = {17},
     number = {5},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZVMMF_1977_17_5_a18/}
}