@incollection{JEDP_1980____A12_0,
     author = {Schiltz, D. and Vaillant, Jean and Wagschal, Claude},
     title = {Probl\`eme de {Cauchy} ramifi\'e : racine caract\'eristique triple en involution},
     booktitle = {},
     series = {Journ\'ees \'equations aux d\'eriv\'ees partielles},
     eid = {12},
     pages = {1--4},
     publisher = {Ecole polytechnique},
     year = {1980},
     zbl = {0445.35009},
     language = {fr},
     url = {http://www.numdam.org/item/JEDP_1980____A12_0/}
}