@article{BSMF_1957__85__283_0,
     author = {Malgrange, Bernard},
     title = {Sur une classe d'op\'erateurs diff\'erentiels hypoelliptiques},
     journal = {Bulletin de la Soci\'et\'e Math\'ematique de France},
     pages = {283--306},
     publisher = {Soci\'et\'e math\'ematique de France},
     volume = {85},
     year = {1957},
     doi = {10.24033/bsmf.1490},
     mrnumber = {21 #5063},
     zbl = {0082.09303},
     language = {fr},
     url = {http://www.numdam.org/articles/10.24033/bsmf.1490/}
}