TSAI, LONG-YI, and S. T. WU. “EXISTENCE OF SOLUTIONS FOR ELLIPTIC INTEGRO-DIFFERENTIAL SYSTEMS”. Tamkang Journal of Mathematics 25, no. 1 (March 1, 1995): 61–70. Accessed May 4, 2024. https://journals.math.tku.edu.tw/index.php/TKJM/article/view/4426.