1. Stankevich, I.V., On one inverse problem of spectral analysis for the Hill
equation, Dokl. Akad. Nauk SSSR, 1970, vol. 192, no. 1,
pp. 34–37.
2. Sadovnichii, V.A., Uniqueness of solution to inverse problem in the case of a
second-order equation with nonsplitting boundary conditions. Regularized sums of part of
eigenvalues. Factorization of characteristic determinant, Dokl. Akad
Nauk SSSR, 1972, vol. 206, no. 2, pp. 293–296.
3. Yurko, V.A., On differential operators with nonsplitting boundary conditions,Funkts. Anal. Ego Prilozh., 1994, vol. 28, no. 4,
pp. 90–92.
4. Marchenko, V.A., Operatory Shturma–Liuvillya i ikh
prilozheniya (Sturm–Liouville Operators and Their Applications), Kiev: Naukova
Dumka, 1977.
5. Sadovnichii, V.A., Sultanaev, Ya.T., and Akhtyamov, A.M., Obratnye
zadachi Shturma–Liuvillya s neraspadayushchimisya kraevymi usloviyami (Inverse
Sturm–Liouville Problems with Nonsplitting Boundary Conditions), Moscow: Izd. Mosk.
Univ., 2009.