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@article{IM2_1968_2_6_a7, author = {M. I. Freidlin}, title = {On the smoothness of solutions of degenerate elliptic equations}, journal = {Izvestiya. Mathematics }, pages = {1337--1359}, publisher = {mathdoc}, volume = {2}, number = {6}, year = {1968}, language = {en}, url = {http://geodesic.mathdoc.fr/item/IM2_1968_2_6_a7/} }
M. I. Freidlin. On the smoothness of solutions of degenerate elliptic equations. Izvestiya. Mathematics , Tome 2 (1968) no. 6, pp. 1337-1359. http://geodesic.mathdoc.fr/item/IM2_1968_2_6_a7/