@incollection{JEDP_1988____A4_0, author = {Bernardi, Enrico and Bove, Antonio}, title = {Conditions de {Levi} pour le probl\`eme de {Cauchy} pour une classe d'\'equations hyperboliques \`a caract\'eristique triples}, booktitle = {}, series = {Journ\'ees \'equations aux d\'eriv\'ees partielles}, eid = {4}, pages = {1--7}, publisher = {Ecole polytechnique}, year = {1988}, mrnumber = {90b:35144b}, zbl = {0676.35053}, language = {fr}, url = {http://archive.numdam.org/item/JEDP_1988____A4_0/} }