@incollection{JEDP_1992____A13_0,
     author = {Colombini, Ferruccio},
     title = {Quelques remarques sur le probl\`eme de {Cauchy} pour des \'equations faiblement hyperboliques},
     booktitle = {},
     series = {Journ\'ees \'equations aux d\'eriv\'ees partielles},
     eid = {13},
     pages = {1--6},
     publisher = {Ecole polytechnique},
     year = {1992},
     mrnumber = {94a:35072},
     zbl = {0779.35069},
     language = {fr},
     url = {http://archive.numdam.org/item/JEDP_1992____A13_0/}
}