@article{RM_1965_20_4_a24,
     author = {M. A. Krasnosel'skii and V. V. Strygin},
     title = {Principles of rotational invariance of a~vector field},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     year = {1965},
     volume = {20},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/RM_1965_20_4_a24/}
}