Balázs, M., and G. Goldner. “On the Approximative Solving of the Integral Equations”. Anal. Numér. Théor. Approx. 6, no. 1 (February 1, 1977): 5–7. Accessed April 11, 2025. https://ictp.acad.ro/jnaat/journal/article/view/1977-vol6-no1-art1.