Abtahi , F., and S. Rahnama. “Essential Amenability of Fréchet Algebras”. Ukrains’kyi Matematychnyi Zhurnal 72, no. 7 (July 15, 2020): 867-876. Accessed October 7, 2022. https://umj.imath.kiev.ua/index.php/umj/article/view/830.