@article{DE_1983_19_12_a2,
     author = {A. A. Kadirov},
     title = {Singular points of differential equations with nonoriented trajectories on a plane},
     journal = {Differencialʹnye uravneni\^a},
     pages = {2039--2048},
     publisher = {mathdoc},
     volume = {19},
     number = {12},
     year = {1983},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1983_19_12_a2/}
}