Altun, I., M. Tanveer, and M. Imdad. “COMMON FIXED POINT THEOREMS OF INTEGRAL TYPE IN MENGER PM SPACES”. Journal of Nonlinear Analysis and Optimization: Theory & Applications, vol. 3, no. 1, Mar. 2012, pp. 55-66, http://www.math.sci.nu.ac.th/ojs302/index.php/jnao/article/view/78.