@article{AM_1999_150_3_a6,
     author = {Barry Simon},
     title = {A new approach to inverse spectral theory. {I:} {Fundamental} formalism},
     journal = {Annals of mathematics},
     publisher = {mathdoc},
     volume = {150},
     number = {3},
     year = {1999},
     url = {http://geodesic.mathdoc.fr/item/AM_1999_150_3_a6/}
}