@article{TIMM_2014_20_4_a3,
     author = {V. I. Berdyshev},
     title = {Linear approximation of vector functions},
     journal = {Trudy Instituta matematiki i mehaniki},
     pages = {38--43},
     year = {2014},
     volume = {20},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TIMM_2014_20_4_a3/}
}