@article{ZNSL_1990_186_a4,
     author = {M. I. Belishev and T. L. Sheronova},
     title = {The methods of the boundary control theory in inverse problem for unhomogeneous string},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {37--49},
     publisher = {mathdoc},
     volume = {186},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1990_186_a4/}
}