Balázs, M. “On a Method for Approximate Solving of Non-Linear Operational Equations”. Anal. Numér. Théor. Approx. 15, no. 2 (August 1, 1986): 105–110. Accessed April 11, 2025. https://ictp.acad.ro/jnaat/journal/article/view/1986-vol15-no2-art2.