@article{IVM_1972_9_a5,
     author = {S. Karimov},
     title = {The characteristic numbers of a~second order linear homogeneous equation with periodic coefficient},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {44--47},
     year = {1972},
     number = {9},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1972_9_a5/}
}