Gheorghiu, Calin-Ioan, and Bertin Zinsou. “Analytic Vs. Numerical Solutions to a Sturm-Liouville Transmission Eigenproblem”. J. Numer. Anal. Approx. Theory 48, no. 2 (January 31, 2020): 159-174. Accessed September 26, 2020. https://ictp.acad.ro/jnaat/journal/article/view/1201.