Vynnyts’kyiB. V., and ShapovalovskiiA. V. 2000. “A Remark on the Completeness of Systems of Exponentials With Weight in $L^2(ℝ)$”. Ukrains’kyi Matematychnyi Zhurnal 52 (7), 875-80. https://umj.imath.kiev.ua/index.php/umj/article/view/4486.