Los’, V.M. and Roitberg, Y.A. (1999) “On the Sobolev problem in the complete scale of Banach spaces”, Ukrains’kyi Matematychnyi Zhurnal, 51(9), pp. 1181–1192. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/4714 (Accessed: 7 April 2025).