@article{ZNSL_1973_34_a2,
     author = {V. M. Babich},
     title = {On the exact justification of short wave approximation in three dimension case},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {23--51},
     year = {1973},
     volume = {34},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1973_34_a2/}
}