Makhmudova, M. G., and A. Kh. Khanmamedov. “On the Spectral Properties of the One-dimensional Stark Operator on the Half-Line”. Ukrains’kyi Matematychnyi Zhurnal 71, no. 11 (November 25, 2019): 1579-1584. Accessed October 5, 2022. http://umj.imath.kiev.ua/index.php/umj/article/view/1537.