“…Among these papers, the existence and multiplicity of solutions or positive solutions for fourth-order boundary value problems were discussed widely by using various methods. Some of the main tools are the lower and upper solution method (see [5,6,8,12]), monotone iterative technique (see [1,2,8,11]), Krasnoselskii fixed point theorem (see [7,17]), fixed point index (see [4,18,23]), Leray-Schauder degree (see [10,12]), bifurcation theory (see [14,19,21]), the critical point theory (see [24]), the shooting method (see [3]) and fixed point theorems on cones (see [13,16,15,22,26,25]). In this paper, we use monotone iterative technique and lower and upper solutions to get the existence of nonzero solutions for the problem (1.1).…”