@incollection{JEDP_1982____A17_0,
     author = {Gourdin, Daniel},
     title = {Inverses d'op\'erateurs faiblement hyperboliques \`a caract\'eristiques de multiplicit\'e variable dans la classe des op\'erateurs de {Volterra}},
     booktitle = {},
     series = {Journ\'ees \'equations aux d\'eriv\'ees partielles},
     eid = {17},
     pages = {1--10},
     publisher = {Ecole polytechnique},
     year = {1982},
     zbl = {0486.35016},
     language = {fr},
     url = {http://www.numdam.org/item/JEDP_1982____A17_0/}
}