BabenkoV. F., KorneichukN. P., and PichugovS. A. “Kolmogorov-Type Inequalities for Mixed Derivatives of Functions of Many Variables”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 56, no. 5, May 2004, pp. 579-94, https://umj.imath.kiev.ua/index.php/umj/article/view/3779.