@article{AFST_1997_6_6_3_525_0,
     author = {Orr\`u, Nicola},
     title = {On a weakly hyperbolic equation with a term of order zero},
     journal = {Annales de la Facult\'e des sciences de Toulouse : Math\'ematiques},
     pages = {525--534},
     publisher = {Universit\'e Paul Sabatier. Facult\'e des sciences},
     address = {Toulouse},
     volume = {Ser. 6, 6},
     number = {3},
     year = {1997},
     mrnumber = {1610911},
     zbl = {0895.35057},
     language = {en},
     url = {http://www.numdam.org/item/AFST_1997_6_6_3_525_0/}
}