Voir la notice de l'article provenant de la source Math-Net.Ru
@article{DE_1977_13_3_a8, author = {P. T. Cherevichny}, title = {The index of a singular point of the equation $y'=\frac{P_4(x,y)}{Q_4(x,y)}$}, journal = {Differencialʹnye uravneni\^a}, pages = {463--467}, publisher = {mathdoc}, volume = {13}, number = {3}, year = {1977}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1977_13_3_a8/} }
P. T. Cherevichny. The index of a singular point of the equation $y'=\frac{P_4(x,y)}{Q_4(x,y)}$. Differencialʹnye uravneniâ, Tome 13 (1977) no. 3, pp. 463-467. http://geodesic.mathdoc.fr/item/DE_1977_13_3_a8/