“Constructing a basis from systems of eigenfunctions of one not strengthened regular boundary value problem” (2018) ҚазҰУ Хабаршысы. Математика, механика, информатика сериясы, 84(1), pp. 36–44. Available at: https://bm.kaznu.kz/index.php/kaznu/article/view/421 (Accessed: 14 July 2026).