1. Levitan B.M. (1967). Inverse Sturm-Liouville Problems. Nauka, Moscow 240 pp. (in Russian)
2. Nelepo B.A., Korotaev G.K., Suetin V.S., and Terehin Yu.V. (1985). Aerospace Radar Imaging of Ocean. Naukova Dumka, Kiev, 168 pp. (in Russian)
3. Potetunko E.N., Cherkesov L.V., Shubin D.S., and Scherback Ye.N. (2001). Free Vibrations and Inverse Spectral Problems. Vuzovskaya Kniga, Moscow 288 pp. (in Russian)
4. Scherback Ye.N. Confidence interval of spectrum of fundamental frequencies of stratified fluid. In: Vorovich I.I.,: Proceedings of IV International Conference Contemporary Problems of Continuum Mechanics. Rostov-on-Don, NCSCHS (1998) pp. 218–221 (in Russian).
5. Ryndina V.V. (2000). Some questions of reconstruction uniqueness of the Brunt-Vaisala frequency by disperse curves. J. Appl. Math. Mech. 64(1):121–126 (in Russian)