@article{DAN_1991_317_4_a2,
     author = {Yu. Yu. Berest},
     title = {Construction of fundamental solutions for {Huygens} equations as},
     journal = {Doklady Akademii Nauk},
     pages = {786--789},
     publisher = {mathdoc},
     volume = {317},
     number = {4},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1991_317_4_a2/}
}