@article{DE_1970_6_11_a4,
     author = {S. G. Kondratenya and A. I. Yablonskii},
     title = {The singular points of the solution of systems of second order differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1970--1975},
     publisher = {mathdoc},
     volume = {6},
     number = {11},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1970_6_11_a4/}
}