@article{AL_1970_9_2_a1,
     author = {L. A. Bokut'},
     title = {Unsolvability of certain algorithmic problems in a class of},
     journal = {Algebra i logika},
     pages = {137--144},
     publisher = {mathdoc},
     volume = {9},
     number = {2},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1970_9_2_a1/}
}