Samoilenko , Y. S., & Shulman , V. S. . (1991). Representations of correlations of the $і [A, B] = f(A) + g(B)$ type. Ukrains’kyi Matematychnyi Zhurnal, 43(1), 110-114. https://umj.imath.kiev.ua/index.php/umj/article/view/9313