Kim, Sung Guen. “Smooth Symmetric Bilinear Forms on ${\mathcal L}_s(^2l_{\infty}^2)$”. Carpathian Mathematical Publications 14, no. 1 (March 29, 2022): 20–28. Accessed March 29, 2025. https://journals.pnu.edu.ua/index.php/cmp/article/view/4658.