Al-Subaihi, I., and A. A. Al-Harbi. “Family of Optimal Eighth-Order of Convergence for Solving Nonlinear Equations”. Journal of Progressive Research in Mathematics, Vol. 4, no. 4, Aug. 2015, pp. 393-8, http://scitecresearch.com/journals/index.php/jprm/article/view/291.