@article{TRSPY_1949_30_a0,
     author = {N. V. Efimov},
     title = {Qualitative problems of the theory of deformations of surfaces in the small},
     journal = {Informatics and Automation},
     pages = {3--128},
     publisher = {mathdoc},
     volume = {30},
     year = {1949},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TRSPY_1949_30_a0/}
}