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@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/} }
Yu. T. Lisitsa. Hopf’s classification theorem in the theory of shapes. Doklady Akademii Nauk, Tome 223 (1975) no. 5, pp. 1056-1059. http://geodesic.mathdoc.fr/item/DAN_1975_223_5_a4/