@article{RM_1974_29_4_a9,
     author = {Yu. A. Brudnyi},
     title = {Local approximations and differentiability of functions of several variables},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     publisher = {mathdoc},
     volume = {29},
     number = {4},
     year = {1974},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/RM_1974_29_4_a9/}
}