Durak, S., and R. Amirov. “INVERSE PROBLEMS FOR DISCONTINOUS COEFFICIENTS STURM-LIOUVILLE OPERATORS DEPENDING ON THE SPECTRAL PARAMETER BOUNDARY CONDITIONS”. Journal of Progressive Research in Mathematics, Vol. 13, no. 1, Jan. 2018, pp. 2135-50, http://scitecresearch.com/journals/index.php/jprm/article/view/1343.