Voir la notice de l'article provenant de la source Math-Net.Ru
@article{MZM_1997_61_5_a14, author = {V. V. Filippov}, title = {Existence of periodic solutions}, journal = {Matemati\v{c}eskie zametki}, pages = {769--784}, publisher = {mathdoc}, volume = {61}, number = {5}, year = {1997}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MZM_1997_61_5_a14/} }
V. V. Filippov. Existence of periodic solutions. Matematičeskie zametki, Tome 61 (1997) no. 5, pp. 769-784. http://geodesic.mathdoc.fr/item/MZM_1997_61_5_a14/