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@article{DAN_1962_144_5_a11, author = {R. R. Mullari}, title = {On the principle directions of an $m$-dimensional surface}, journal = {Doklady Akademii Nauk}, pages = {989--992}, publisher = {mathdoc}, volume = {144}, number = {5}, year = {1962}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1962_144_5_a11/} }
R. R. Mullari. On the principle directions of an $m$-dimensional surface. Doklady Akademii Nauk, Tome 144 (1962) no. 5, pp. 989-992. http://geodesic.mathdoc.fr/item/DAN_1962_144_5_a11/