@article{ZNSL_1985_148_a0,
     author = {V. D. Azhotkin},
     title = {Space-time caustic of wave field in anisotropic media},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {5--12},
     publisher = {mathdoc},
     volume = {148},
     year = {1985},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1985_148_a0/}
}