“…It is well known that monotone iterative technique is quite useful, see [3,13,14,15,16,17] and references therein. In [5,6,7,9,22], this method, combining upper and lower solutions, has been successfully applied to obtain the existence of extremal solutions for boundary value problems with integral boundary conditions. Bhaskar [4] and West [18] developed monotone iterative method, considered the generalized monotone iterative method for initial value problems, obtained the existence of extremal solutions for differential equations where the forcing function is the sum of two monotone functions, one of which is monotone non-decreasing and the other is non-increasing.…”