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@article{IVM_1973_2_a13, author = {I. D. Cherkasov}, title = {Transformation of second order linear equations}, journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika}, pages = {106--115}, publisher = {mathdoc}, number = {2}, year = {1973}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/IVM_1973_2_a13/} }
I. D. Cherkasov. Transformation of second order linear equations. Izvestiâ vysših učebnyh zavedenij. Matematika, no. 2 (1973), pp. 106-115. http://geodesic.mathdoc.fr/item/IVM_1973_2_a13/