Kal’menov, T.Sh., and G.D. Arepova. “A Criterion for the Existence of Soliton Solutions of Telegraph Equation”. Bulletin of the Karaganda University. Mathematics Series 91, no. 3 (September 29, 2018): 45–52. Accessed July 10, 2025. https://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/240.