@article{ZVMMF_1999_39_5_a8,
     author = {A. B. Vasil'eva and E. N. Rykhlinskaya},
     title = {On contrast structures of variable type},
     journal = {\v{Z}urnal vy\v{c}islitelʹnoj matematiki i matemati\v{c}eskoj fiziki},
     pages = {792--800},
     publisher = {mathdoc},
     volume = {39},
     number = {5},
     year = {1999},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZVMMF_1999_39_5_a8/}
}