@article{DE_1989_25_2_a1,
     author = {L. M. Berkovich},
     title = {Second-order kindred linear differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {192--201},
     publisher = {mathdoc},
     volume = {25},
     number = {2},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1989_25_2_a1/}
}