Burskii VP, Zhedanov AS. On Dirichlet problem for string equation, Poncelet problem, Pell-Abel equation, and some other related problems. Ukr. Mat. Zhurn. [Internet]. 2006Apr.25 [cited 2024Apr.20];58(4):435–450. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/3466