@article{DAN_1979_245_4_a15,
     author = {L. A. Ivanov},
     title = {Huygens principle for equations dissociating into factors},
     journal = {Doklady Akademii Nauk},
     pages = {829--832},
     publisher = {mathdoc},
     volume = {245},
     number = {4},
     year = {1979},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1979_245_4_a15/}
}