@article{DAN_1975_223_5_a4,
     author = {Yu. T. Lisitsa},
     title = {Hopf{\textquoteright}s classification theorem in the theory of shapes},
     journal = {Doklady Akademii Nauk},
     pages = {1056--1059},
     publisher = {mathdoc},
     volume = {223},
     number = {5},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1975_223_5_a4/}
}