Y. M. Berezansky, “On self-conjugation of field operators and integral representations of Whiteman functionals ”, Ukr. Mat. Zhurn., vol. 18, no. 3, pp. 3–12, Apr. 1966, Accessed: Apr. 09, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/8732