@article{IM2_1978_12_1_a6,
     author = {B. M. Levitan},
     title = {On the determination of the {Sturm--Liouville} operator from one and two spectra},
     journal = {Izvestiya. Mathematics },
     pages = {179--193},
     publisher = {mathdoc},
     volume = {12},
     number = {1},
     year = {1978},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1978_12_1_a6/}
}