@incollection{JEDP_1986____A3_0, author = {Wagschal, Claude}, title = {Probl\`eme de {Cauchy} ramifi\'e \`a caract\'eristiques tangentes}, booktitle = {}, series = {Journ\'ees \'equations aux d\'eriv\'ees partielles}, eid = {3}, pages = {1--8}, publisher = {Ecole polytechnique}, year = {1986}, mrnumber = {874545}, zbl = {0627.35012}, language = {fr}, url = {http://archive.numdam.org/item/JEDP_1986____A3_0/} }