@incollection{AST_1973__2-3__135_0,
     author = {Chazarain, Jacques},
     title = {Une classe d'op\'erateurs \`a caract\'eristiques de multiplicit\'e constante},
     booktitle = {Colloque International C.N.R.S. sur les \'equations aux d\'eriv\'ees partielles lin\'eaires},
     series = {Ast\'erisque},
     pages = {135--142},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {2-3},
     year = {1973},
     mrnumber = {393785},
     zbl = {0271.35056},
     language = {fr},
     url = {http://www.numdam.org/item/AST_1973__2-3__135_0/}
}