Aharonyan, N. G. “ PLEIJEL TYPE IDENTITIES”. Proceedings of the YSU A: Physical and Mathematical Sciences 43, no. 2 (219) (June 26, 2009): 32–37. Accessed July 22, 2024. https://journals.ysu.am/index.php/proceedings-phys-math/article/view/vol43_no2_2009_pp032-037.