Tsetimi, J., D. A. B., and O. K.O. “Certain Orthogonal Polynomials for Solving Boundary Value Problems Using the Variational Iteration Method”. Boson Journal of Modern Physics, Vol. 7, no. 1, Sept. 2020, pp. 12-19, http://scitecresearch.com/journals/index.php/bjmp/article/view/1601.