Deineka, V. S., Sergienko, I. V., & Skopetskii, V. V. (1999). Eigenvalue problems with discontinuous eigenfunctions and their numerical solutions. Ukrains’kyi Matematychnyi Zhurnal, 51(10), 1317–1323. Retrieved from https://umj.imath.kiev.ua/index.php/umj/article/view/4730