Voir la notice de l'article provenant de la source Math-Net.Ru
@article{DE_1968_4_4_a7, author = {V. P. Skripnik}, title = {Degenerate systems and a small parameter at the derivative}, journal = {Differencialʹnye uravneni\^a}, pages = {646--658}, publisher = {mathdoc}, volume = {4}, number = {4}, year = {1968}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1968_4_4_a7/} }
V. P. Skripnik. Degenerate systems and a small parameter at the derivative. Differencialʹnye uravneniâ, Tome 4 (1968) no. 4, pp. 646-658. http://geodesic.mathdoc.fr/item/DE_1968_4_4_a7/