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@article{DAN_1969_188_5_a12, author = {I. D. Stupina}, title = {Certain properties of $R$- and $R^c$-operations}, journal = {Doklady Akademii Nauk}, pages = {1010--1013}, publisher = {mathdoc}, volume = {188}, number = {5}, year = {1969}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1969_188_5_a12/} }
I. D. Stupina. Certain properties of $R$- and $R^c$-operations. Doklady Akademii Nauk, Tome 188 (1969) no. 5, pp. 1010-1013. http://geodesic.mathdoc.fr/item/DAN_1969_188_5_a12/