@article{MMO_1981_43_a2,
     author = {V. Ya. Ivriǐ},
     title = {Propagation of singularities of solutions of nonclassical boundary value problems for second-order hyperbolic equations},
     journal = {Trudy Moskovskogo matemati\v{c}eskogo ob\^{s}estva},
     pages = {81--91},
     publisher = {mathdoc},
     volume = {43},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MMO_1981_43_a2/}
}