@article{CRMATH_2009__347_19-20_1129_0,
     author = {Boularas, Driss},
     title = {Th\'eor\`eme de {Poincar\'e{\textendash}Lyapunov} et conditions n\'ecessaires d'existence d'un centre},
     journal = {Comptes Rendus. Math\'ematique},
     pages = {1129--1134},
     publisher = {Elsevier},
     volume = {347},
     number = {19-20},
     year = {2009},
     doi = {10.1016/j.crma.2009.07.009},
     language = {fr},
     url = {http://www.numdam.org/articles/10.1016/j.crma.2009.07.009/}
}