@article{ZVMMF_1986_26_9_a12,
     author = {V. F. Apel'tsin and A. S. Il'inskii and B. R. Sabitov},
     title = {Approximation of vector fields},
     journal = {\v{Z}urnal vy\v{c}islitelʹnoj matematiki i matemati\v{c}eskoj fiziki},
     pages = {1412--1415},
     year = {1986},
     volume = {26},
     number = {9},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZVMMF_1986_26_9_a12/}
}