Denysyuk, I. T. “Problem of Conjugation of Solutions of the Lame Wave Equation in Domains With Piecewise-Smooth Boundaries”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 57, no. 1, Jan. 2005, pp. 32–46, https://umj.imath.kiev.ua/index.php/umj/article/view/3572.