@article{IVM_1964_1_a19,
     author = {M. E. Tsypkin},
     title = {An expression for the measures of curvature and torsion for an unusual ruled surface},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {144--152},
     publisher = {mathdoc},
     number = {1},
     year = {1964},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1964_1_a19/}
}