Sengupta, Debasish. “The Asymptotic Laws of the Distribution of Eigenvalues for a System of Second Order Differential Equations Having Turning Points at Both Ends of the Interval”. The Journal of the Indian Mathematical Society 90, no. 1-2 (March 24, 2023): 13–22. Accessed August 25, 2024. https://informaticsjournals.com/index.php/jims/article/view/26380.