@article{DAN_1981_257_4_a18,
     author = {V. P. Palamodov},
     title = {Singularities of the solutions of strictly hyperbolic equations and the problem of quasar twins in astronomy},
     journal = {Doklady Akademii Nauk},
     pages = {849--852},
     year = {1981},
     volume = {257},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1981_257_4_a18/}
}