Alzugaray, M. T. (2002). On growth and domains of holomorphy of functions that are analytic in a disk and generate Pólya frequency sequences. Математическая физика, анализ, геометрия, 9(2), 281–284. вилучено із https://mag.ilt.kharkiv.ua/index.php/mag/article/view/m09-0281e