Storozh, O. G., and Iu. I. Oliiar. “On a Criterion of Mutual Adjointness for Extensions of Some Nondensely Defined Operators”. Methods of Functional Analysis and Topology 20, no. 1 (March 25, 2014): 50–58. Accessed February 4, 2026. https://zen.imath.kiev.ua/index.php/mfat/article/view/566.