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@article{IVM_1989_4_a6, author = {I. S. Kac}, title = {An unnoticed condition of nonoscillation and its corollaries}, journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika}, pages = {46--51}, publisher = {mathdoc}, number = {4}, year = {1989}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/IVM_1989_4_a6/} }
I. S. Kac. An unnoticed condition of nonoscillation and its corollaries. Izvestiâ vysših učebnyh zavedenij. Matematika, no. 4 (1989), pp. 46-51. http://geodesic.mathdoc.fr/item/IVM_1989_4_a6/