V. V. Volchkov, V. V. Volchkov, and I. M. Savost’yanova, “One Problem Connected with the Helgason Support Problem”, Ukr. Mat. Zhurn., vol. 67, no. 9, pp. 1189–1200, Sep. 2015, Accessed: Dec. 05, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/2058