M. I. Kadets, “On absolute, perfect, and unconditional convergences of double series in Banach spaces”, Ukr. Mat. Zhurn., vol. 49, no. 8, pp. 1032–1041. August, Aug. 1997, Accessed: Feb. 17, 2026. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/5098