@article{UZKU_1963_123_1_a10,
     author = {B. N. Shapukov},
     title = {Surfaces and singular directions in a~bilinear metric space of linear elements},
     journal = {U\v{c}\"enye zapiski Kazanskogo universiteta. Seri\^a Fiziko-matemati\v{c}eskie nauki},
     pages = {180--195},
     publisher = {mathdoc},
     volume = {123},
     number = {1},
     year = {1963},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/UZKU_1963_123_1_a10/}
}