VirchenkoN. A., and Sichkar’Y. V. “On Some Integral Equations With the Generalized Legendre Function”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 51, no. 2, Feb. 1999, pp. 263–267, https://umj.imath.kiev.ua/index.php/umj/article/view/4607.