@article{SM_1987_58_1_a14,
     author = {A. Khaidarov},
     title = {Carleman estimates and inverse problems for second-order hyperbolic equations},
     journal = {Sbornik. Mathematics},
     pages = {267--277},
     publisher = {mathdoc},
     volume = {58},
     number = {1},
     year = {1987},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1987_58_1_a14/}
}