@article{RM_1961_16_2_a8,
     author = {S. G. Gasparyan},
     title = {The definition of the fourth fundamental tensor of a~surface in terms of the metric and mean curvature},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     publisher = {mathdoc},
     volume = {16},
     number = {2},
     year = {1961},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/RM_1961_16_2_a8/}
}