@article{SEDP_1980-1981____A11_0,
     author = {Komatsu, H.},
     title = {Hyperbolic equations and irregularity},
     journal = {S\'eminaire \'Equations aux d\'eriv\'ees partielles (Polytechnique) dit aussi "S\'eminaire Goulaouic-Schwartz"},
     note = {talk:9 bis},
     pages = {1--16},
     publisher = {Ecole Polytechnique, Centre de Math\'ematiques},
     year = {1980-1981},
     zbl = {0497.35060},
     language = {en},
     url = {http://www.numdam.org/item/SEDP_1980-1981____A11_0/}
}