@article{SM_1988_60_1_a5,
     author = {B. M. Levitan},
     title = {Sturm-liouville operators on the whole line, with the same discrete spectrum},
     journal = {Sbornik. Mathematics},
     pages = {77--106},
     publisher = {mathdoc},
     volume = {60},
     number = {1},
     year = {1988},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1988_60_1_a5/}
}