@article{DAN_1992_323_5_a9,
     author = {V. A. Sharafutdinov},
     title = {Quasi-isotropic approximation of geometric optics, and tomography},
     journal = {Doklady Akademii Nauk},
     pages = {847--850},
     publisher = {mathdoc},
     volume = {323},
     number = {5},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1992_323_5_a9/}
}