@article{MMO_1977_34_a3,
     author = {V. Ya. Ivriǐ},
     title = {Correctness of the {Cauchy} problem for nonstrictly hyperbolic {operators.~III.} {The} energy integral},
     journal = {Trudy Moskovskogo matemati\v{c}eskogo ob\^{s}estva},
     pages = {151--170},
     publisher = {mathdoc},
     volume = {34},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MMO_1977_34_a3/}
}