@article{DAN_1975_221_4_a5,
     author = {V. Ya. Ivrii},
     title = {Conditions for the correctness in {Gevrey} classes of the {Cauchy} problem for nonstrictly hyperbolic operators},
     journal = {Doklady Akademii Nauk},
     pages = {775--777},
     publisher = {mathdoc},
     volume = {221},
     number = {4},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1975_221_4_a5/}
}