@article{JEDP_1980____A1_0,
     author = {Alinhac, Serge and Zuily, Claude},
     title = {Unicit\'e et non unicit\'e du probl\`eme de {Cauchy} pour des op\'erateurs hyperboliques \`a caract\'eristiques doubles},
     journal = {Journ\'ees \'equations aux d\'eriv\'ees partielles},
     eid = {1},
     pages = {1--5},
     publisher = {Ecole polytechnique},
     year = {1980},
     zbl = {0445.35070},
     language = {fr},
     url = {http://www.numdam.org/item/JEDP_1980____A1_0/}
}