SоlоmkаО. P. “A Theorem on Boundary Properties of One Class of Functions Analytical in the Plain With a Cut ”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 23, no. 6, Oct. 1971, pp. 818-23, https://umj.imath.kiev.ua/index.php/umj/article/view/8634.