Li, Chi-Kwong, and Nam-Kiu Tsing. “NORMS ON CARTESIAN PRODUCT OF LINEAR SPACES”. Tamkang Journal of Mathematics 21, no. 1 (March 1, 1990): 35–39. Accessed April 26, 2024. https://journals.math.tku.edu.tw/index.php/TKJM/article/view/4692.