Approximation of four step iteration scheme with errors on closed convex subsets of normed linear spaces

##article.abstract##

This paper investigates the convergence of four-step iteration schemes with error terms defined on closed convex subsets of normed linear spaces. Sufficient conditions are established for convergence to a fixed point of certain classes of norm linear operators. The results extend and unify several known theorems in fixed point approximation theory such as Berinde [9], Agarwal [11], Bosede [3] and Wasfi [6].