Slyusarchuk, V. Y. (2020). Equations in a Hilbert space whose solution sets are invariant with respect to a group isomorphic to a one-parameter group of unitary operators. *Ukrainsâ€™kyi Matematychnyi Zhurnal*, *72*(1), 86-99. Retrieved from https://umj.imath.kiev.ua/index.php/umj/article/view/687