@article{CRMATH_2004__339_11_763_0,
     author = {Duval, Guillaume},
     title = {Valuations invariantes pour l'action des groupes de {Galois} diff\'erentiels},
     journal = {Comptes Rendus. Math\'ematique},
     pages = {763--768},
     publisher = {Elsevier},
     volume = {339},
     number = {11},
     year = {2004},
     doi = {10.1016/j.crma.2004.05.021},
     language = {fr},
     url = {http://www.numdam.org/articles/10.1016/j.crma.2004.05.021/}
}