Velesnitskii, V.F. and Semenchuk, V.N. (2012) “On one Shemetkov problem”, Ukrains’kyi Matematychnyi Zhurnal, 64(9), pp. 1282–1288. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/2658 (Accessed: 5 December 2025).