Ourraoui, A. “AN EXISTENCE RESULT FOR AN ELLIPTIC PROBLEM INVOLVING A FOURTH ORDER OPERATOR”. Journal of Nonlinear Analysis and Optimization: Theory & Applications (JNAO), vol. 7, no. 2, Jan. 2018, pp. 51-56, https://ph03.tci-thaijo.org/index.php/jnao/article/view/2831.