@article{SEDP_1973-1974____A6_0,
     author = {Helffer, B.},
     title = {Op\'erateurs pseudo-diff\'erentiels et r\'esolubilit\'e locale (d'apr\`es {R.} {Beals} et {C.} {Feffermann)}},
     journal = {S\'eminaire \'Equations aux d\'eriv\'ees partielles (Polytechnique) dit aussi "S\'eminaire Goulaouic-Schwartz"},
     note = {talk:7},
     pages = {1--11},
     publisher = {Ecole Polytechnique, Centre de Math\'ematiques},
     year = {1973-1974},
     mrnumber = {410475},
     zbl = {0337.35066},
     language = {fr},
     url = {http://www.numdam.org/item/SEDP_1973-1974____A6_0/}
}