Bondar, A. V. “On Differentiability of Mappings of Finite-Dimensional Domains into Banach Spaces”. Ukrains’kyi Matematychnyi Zhurnal 51, no. 1 (January 25, 1999): 3–11. Accessed February 9, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/4578.