References
- Chadan , K. and Sabatier , P.C. 1977 . “ Inverse problems in quantum scattering theory ” . New York-Heidelberg-Berlin : Springer .
- Denisov , A. 1989 . Inverse problems for nonlinear ordinary differential equations . Dokl.Akad.Nauk , 307 : 1040 – 1042 . in Russian
- Levitan , B.M. 1984 . “ Sturm-Liouville inverse problems ” . Moscow : Nauka . in Russian
- A.Lorenzi: An inverse spectral problem for a nonlinear ordinary equation, preprint n.40/89 of the Università degli Studi di Mila-no.