Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{PORMA_1965__24_3_114958, author = {van Vleck, F.S.}, title = {A bifurcation theorem for a class of differential equations}, journal = {Portugaliae mathematica}, pages = {125--130}, publisher = {mathdoc}, volume = {24}, number = {3}, year = {1965}, mrnumber = {0222369}, zbl = {0161.28901}, language = {en}, url = {http://geodesic.mathdoc.fr/item/PORMA_1965__24_3_114958/} }
van Vleck, F.S. A bifurcation theorem for a class of differential equations. Portugaliae mathematica, Tome 24 (1965) no. 3, pp. 125-130. http://geodesic.mathdoc.fr/item/PORMA_1965__24_3_114958/