1. A note on the Titchmarsh-Weyl m-function;Bennewitz,1987
2. Formulas for traces for a singular Sturm-Liouville differential operator;Buslaev;Dokl. Akad, Nauk SSSR,1960
3. Inverse Problems in Quantum Scattering Theory;Chadan,1977
4. Analytic Functions;Evgrafov,1966