Bazalii, B. V., and N. V. Vasil'eva. 2000. “On the Solvability of the Hele–Shaw Model Problem in Weighted Hölder Spaces in a Plane Angle”. Ukrains’kyi Matematychnyi Zhurnal 52 (11): 1446-57. https://umj.imath.kiev.ua/index.php/umj/article/view/4552.