@article{DE_1976_12_8_a0,
     author = {O. Boruvka},
     title = {Theory of the global properties of second order linear ordinary differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1347--1383},
     publisher = {mathdoc},
     volume = {12},
     number = {8},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1976_12_8_a0/}
}