@article{ZVMMF_1966_6_1_a15,
     author = {V. Ya. Gol'din and N. N. Kalitkin},
     title = {Finding the solutions of constant sign of ordinary differential equations},
     journal = {\v{Z}urnal vy\v{c}islitelʹnoj matematiki i matemati\v{c}eskoj fiziki},
     pages = {162--163},
     publisher = {mathdoc},
     volume = {6},
     number = {1},
     year = {1966},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZVMMF_1966_6_1_a15/}
}