@article{RSMUP_1995__93__87_0,
     author = {Petrini, Milena},
     title = {A result on the well posedness of the {Cauchy} problem for a class of hyperbolic operators with double characteristics},
     journal = {Rendiconti del Seminario Matematico della Universit\`a di Padova},
     pages = {87--102},
     publisher = {Seminario Matematico of the University of Padua},
     volume = {93},
     year = {1995},
     mrnumber = {1354351},
     zbl = {0836.47037},
     language = {en},
     url = {http://archive.numdam.org/item/RSMUP_1995__93__87_0/}
}