@article{DAN_1966_171_6_a9,
     author = {M. M. Lavrent'ev and V. G. Romanov},
     title = {Three linearized inverse problems for hyperbolic equations},
     journal = {Doklady Akademii Nauk},
     pages = {1279--1281},
     year = {1966},
     volume = {171},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1966_171_6_a9/}
}