BoichukО. A., Zhuravlev, V. F., & PokutnyiО. О. (2013). Normally solvable operator equations in a Banach space. Ukrains’kyi Matematychnyi Zhurnal, 65(2), 163-174. Retrieved from https://umj.imath.kiev.ua/index.php/umj/article/view/2411