@article{AL_1973_12_2_a4,
     author = {G. N. Kobzev},
     title = {btt-reducibility.~I},
     journal = {Algebra i logika},
     pages = {190--204},
     publisher = {mathdoc},
     volume = {12},
     number = {2},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1973_12_2_a4/}
}