@article{SEDP_1973-1974____A16_0,
     author = {Zuily, C.},
     title = {Hypoellipticit\'e des op\'erateurs diff\'erentiels du second ordre \`a coefficients r\'eels},
     journal = {S\'eminaire \'Equations aux d\'eriv\'ees partielles (Polytechnique) dit aussi "S\'eminaire Goulaouic-Schwartz"},
     note = {talk:17},
     pages = {1--11},
     publisher = {Ecole Polytechnique, Centre de Math\'ematiques},
     year = {1973-1974},
     mrnumber = {437904},
     language = {fr},
     url = {http://www.numdam.org/item/SEDP_1973-1974____A16_0/}
}