@article{TRSPY_1962_66_a13,
     author = {V. P. Il'in and V. A. Solonnikov},
     title = {Some properties of differentiable functions of several variables},
     journal = {Informatics and Automation},
     pages = {205--226},
     publisher = {mathdoc},
     volume = {66},
     year = {1962},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TRSPY_1962_66_a13/}
}