@article{SJL_1964___1_72_0,
     author = {Leray, Jean and Waelbroeck, Lucien},
     title = {Norme formelle d'une fonction compos\'ee (pr\'eliminaire \`a l'\'etude des syst\`emes non lin\'eaires, hyperboliques non stricts)},
     journal = {S\'eminaire Jean Leray},
     pages = {72--82},
     publisher = {Coll\`ege de France},
     number = {1},
     year = {1964},
     language = {fr},
     url = {http://archive.numdam.org/item/SJL_1964___1_72_0/}
}