1. Andersson L.-E., “Inverse eigenvalue problems with discontinuous coefficients,” Inverse Probl., 4, No. 2, 353–397 (1988).
2. Andersson L.-E., “Inverse eigenvalue problems for a Sturm-Liouville equation in impedance form,” Inverse Probl., 4, No. 4, 929–971 (1988).
3. Carlson R., “An inverse spectral problem for Sturm-Liouville operators with discontinuous coefficients,” Proc. Amer. Math. Soc., 120, No. 2, 475–484 (1994).
4. Shepelsky D. G., “The inverse problem of reconstruction of the medium’s conductivity in a class of discontinuous and increasing functions,” Adv. Soviet Math., 19, 209–231 (1994).
5. Shestakov I. P., “The inverse spectral problem for the Sturm-Liouville operators with discontinuous coefficients,” Siberian Math. J., 44, No. 5, 891–907 (2003).