Trynin, Alexandr. “Method for Solving Mixed Boundary Value Problems for Parabolic Type Equations by Using Modifications Lagrange-Sturm-Liouville Operators”. Modern Mathematical Methods 2, no. 3 (December 11, 2024): 172–188. Accessed March 13, 2025. https://modernmathmeth.com/index.php/pub/article/view/37.