@article{FPM_1995_1_2_a6,
     author = {E. A. Lapshin},
     title = {The definition of acoustic signal propagation domain},
     journal = {Fundamentalʹna\^a i prikladna\^a matematika},
     pages = {431--454},
     publisher = {mathdoc},
     volume = {1},
     number = {2},
     year = {1995},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FPM_1995_1_2_a6/}
}