@article{RM_1965_20_1_a7,
     author = {M. A. Akivis},
     title = {On an invariant differential-geometric characteristic of the {Dupin} cyclide},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     publisher = {mathdoc},
     volume = {20},
     number = {1},
     year = {1965},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/RM_1965_20_1_a7/}
}