@article{ZNSL_1987_165_a2,
     author = {M. I. Belishev},
     title = {Equations of {Gel'fand{\textendash}Levitan} type in multidimensional inverse problem for the wave equation},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {15--20},
     year = {1987},
     volume = {165},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1987_165_a2/}
}