@article{SJL_1963-1964___2_46_0,
     author = {Vaillant, Jean},
     title = {Caract\'eristiques multiples des syst\`emes d'\'equations aux d\'eriv\'ees partielles lin\'eaires et \`a coefficients constants},
     journal = {S\'eminaire Jean Leray},
     pages = {46--67},
     publisher = {Coll\`ege de France},
     number = {2},
     year = {1963-1964},
     language = {fr},
     url = {http://www.numdam.org/item/SJL_1963-1964___2_46_0/}
}