Volpert, Vitaly, and Vitali Vougalter. “Solvability in the Sense of Sequences for Some Non-Fredholm Elliptic Problems”. Discontinuity, Nonlinearity, and Complexity 2, no. 4 (August 17, 2026): 389–399. Accessed August 17, 2026. https://lhscientificpublishing.com/index.php/DNC/article/view/2061.