@article{SJL_1964-1965___2_16_0,
     author = {Leray, Jean and Ohya, Yujiro},
     title = {\'Equations et syst\`emes non-lin\'eaires, hyperboliques non-stricts},
     journal = {S\'eminaire sur les \'equations aux d\'eriv\'ees partielles},
     pages = {16--76},
     year = {1964-1965},
     publisher = {Coll\`ege de France},
     number = {2},
     language = {fr},
     url = {https://www.numdam.org/item/SJL_1964-1965___2_16_0/}
}