KofanovV. A., and Miropol’skiiV. E. “On Sharp Kolmogorov-Type Inequalities Taking into Account the Number of Sign Changes of Derivatives”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 60, no. 12, Dec. 2008, pp. 1642–1649, https://umj.imath.kiev.ua/index.php/umj/article/view/3278.