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@article{IVM_1958_6_a21, author = {A. Z. Petrov}, title = {lassification of gravitational fields of general form}, journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika}, pages = {226--232}, publisher = {mathdoc}, number = {6}, year = {1958}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/IVM_1958_6_a21/} }
A. Z. Petrov. lassification of gravitational fields of general form. Izvestiâ vysših učebnyh zavedenij. Matematika, no. 6 (1958), pp. 226-232. http://geodesic.mathdoc.fr/item/IVM_1958_6_a21/