Van Ruy, Dinh. “A NONEXISTENCE THEOREM FOR POSITIVE SOLUTION OF THE NONLINEAR INTEGRAL EQUATION”. Science and Technology Development Journal 5, no. 12 (December 31, 2002): 5-10. Accessed December 22, 2024. http://stdj.scienceandtechnology.com.vn/index.php/stdj/article/view/3458.