Balázs, M., and G. Goldner. “On the Approximate Solution of Operator Equations in Hilbert Space by a Steffensen-Type Method”. Anal. Numér. Théor. Approx. 17, no. 1 (February 1, 1988): 19–23. Accessed December 21, 2024. https://ictp.acad.ro/jnaat/journal/article/view/1988-vol17-no1-art3.