@article{SM_1975_25_3_a2,
     author = {V. Ya. Ivrii},
     title = {Correctness of the {Cauchy} problem {in~Gevrey} classes for nonstrictly hyperbolic operators},
     journal = {Sbornik. Mathematics},
     pages = {365--387},
     publisher = {mathdoc},
     volume = {25},
     number = {3},
     year = {1975},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1975_25_3_a2/}
}