Ivanov А. F., et al. “Oleksandr Mykolaiovych Sharkovs’kyi (on His 80th Birthday)”. Ukrains’kyi Matematychnyi Zhurnal, vol. 69, no. 2, Feb. 2017, pp. 257-60, https://umj.imath.kiev.ua/index.php/umj/article/view/1690.