Babenko, V. F., V. A. Kofanov, and S. A. Pichugov. 1997. “On Additive Inequalities for Intermediate Derivatives of Functions Given on a Finite Interval”. Ukrains’kyi Matematychnyi Zhurnal 49 (5): 619–628. https://umj.imath.kiev.ua/index.php/umj/article/view/5042.