@article{MAN_1967__170_161535,
     author = {J. LERAY and Y. OHYA},
     title = {\'Equations et {Syst\`emes} {Non-Lin\'eaires,} {Hyperboliques} {Non-Stricts.}},
     journal = {Mathematische Annalen},
     pages = {167--205},
     publisher = {mathdoc},
     volume = {170},
     year = {1967},
     zbl = {0146.33701},
     url = {http://geodesic.mathdoc.fr/item/MAN_1967__170_161535/}
}