@article{ZNSL_1983_128_a19,
     author = {Z. A. Yanson},
     title = {Asymptotics of solutions of the {Helmholtz} equation in a~region of caustic {shadow~I.}},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {172--185},
     publisher = {mathdoc},
     volume = {128},
     year = {1983},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1983_128_a19/}
}