“Determination of an Exact Solution to the Integral Gelfand - Levitan - Marchenko Equation for the Sturm - Liouville Operators With the Step-Type Potential”. Neliniini Kolyvannya 6, no. 1 (March 29, 2003): 74–82. Accessed January 22, 2026. https://twinhead.imath.kiev.ua/index.php/nosc/article/view/250.