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@article{IVM_1971_6_a2, author = {B. G. Gabdulkhaev}, title = {Certain questions of the theory of approximate {methods.~IV}}, journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika}, pages = {15--23}, publisher = {mathdoc}, number = {6}, year = {1971}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/IVM_1971_6_a2/} }
B. G. Gabdulkhaev. Certain questions of the theory of approximate methods.~IV. Izvestiâ vysših učebnyh zavedenij. Matematika, no. 6 (1971), pp. 15-23. http://geodesic.mathdoc.fr/item/IVM_1971_6_a2/