Kalmenov, T., Shaldanbayev, A., Akylbayev, M., & Urmatova, A. (2020). ON COMPLETENESS OF ROOT VECTORS OF THE CAUCHY PROBLEM OF THE FIRST ORDER EQUATION WITH DEVIATING ARGUMENT. Известия НАН РК. Серия физико-математическая, (2), 50–57. извлечено от http://189185.vm7pq.group/physics-mathematics/article/view/400