@article{SEDP_1976-1977____A9_0,
     author = {Menikoff, A.},
     title = {Hypoelliptic operators with double characteristics},
     journal = {S\'eminaire \'Equations aux d\'eriv\'ees partielles (Polytechnique) dit aussi "S\'eminaire Goulaouic-Schwartz"},
     note = {talk:10},
     pages = {1--8},
     publisher = {Ecole Polytechnique, Centre de Math\'ematiques},
     year = {1976-1977},
     mrnumber = {492800},
     zbl = {0446.35032},
     language = {en},
     url = {http://www.numdam.org/item/SEDP_1976-1977____A9_0/}
}