Nemati, Somayeh, and Y. Ordokhani. “SOLVING NONLINEAR TWO-DIMENSIONAL VOLTERRA INTEGRAL EQUATIONS OF THE FIRST-KIND USING BIVARIATE SHIFTED LEGENDRE FUNCTIONS”. International Journal of Mathematical Modelling & Computations, vol. 5, no. 3, Mar. 2015, pp. 219-30, https://oiccpress.com/ijm2c/article/view/11252.