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@article{IVM_1966_1_a8, author = {F. I. Kagan}, title = {The operation of an infinitesimal $S$-extension}, journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika}, pages = {66--78}, publisher = {mathdoc}, number = {1}, year = {1966}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/IVM_1966_1_a8/} }
F. I. Kagan. The operation of an infinitesimal $S$-extension. Izvestiâ vysših učebnyh zavedenij. Matematika, no. 1 (1966), pp. 66-78. http://geodesic.mathdoc.fr/item/IVM_1966_1_a8/