Avdelas, G., and A. Hadjidimos. “The Numerical Solution of the Self-Adjoint Second Order Eliptic Partial Differential Equation under Mixed Boundary Conditions”. Anal. Numér. Théor. Approx. 7, no. 2 (August 1, 1978): 117–133. Accessed May 2, 2024. https://ictp.acad.ro/jnaat/journal/article/view/1978-vol7-no2-art1.