Aldashev, S. A. “Eigenvalues and Eigenfunctions of the Gellerstedt Problem for the Multidimensional Lavrent?Ev?Bitsadze Equation”. Ukrains’kyi Matematychnyi Zhurnal 63, no. 6 (June 25, 2011): 827-832. Accessed April 26, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/2765.