IslomovB. I., OchilovaN. K., and SadaranganiK. S. “On a Frankl-Type Boundary-Value problem for a Mixed-Type Degenerating Equation”. Ukrains’kyi Matematychnyi Zhurnal 71, no. 10 (October 25, 2019): 1347-1359. Accessed September 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/1519.