@article{ASENS_1997_4_30_6_719_0,
     author = {Chemin, Jean-Yves and Xu, Chao-Jian},
     title = {Inclusions de {Sobolev} en calcul de {Weyl-H\"ormander} et champs de vecteurs sous-elliptiques},
     journal = {Annales scientifiques de l'\'Ecole Normale Sup\'erieure},
     pages = {719--751},
     publisher = {Elsevier},
     volume = {4e s{\'e}rie, 30},
     number = {6},
     year = {1997},
     doi = {10.1016/s0012-9593(97)89937-5},
     mrnumber = {98i:35026},
     zbl = {0892.35161},
     language = {fr},
     url = {http://www.numdam.org/articles/10.1016/s0012-9593(97)89937-5/}
}