ShabozovM. S. “On the Renewal of a Solution of the Dirichlet Boundary-Value Problem for a Biharmonic Equation”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 50, no. 8, Aug. 1998, pp. 1147–1151, https://umj.imath.kiev.ua/index.php/umj/article/view/4865.