Vestfrid, I. A. “Isometric Imbedding of Some Metric Spaces in l<sub class="a-Plus-plus">p</Sub&gt;-Spaces”. Ukrains’kyi Matematychnyi Zhurnal 53, no. 12 (December 25, 2001): 1718-1723. Accessed May 18, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/4389.