Sidenko, N. R. “Averaging of the Dirichlet Problem for a Special Hyperbolic Kirchhoff Equation”.
Ukrains’kyi Matematychnyi Zhurnal 58, no. 2 (February 25, 2006): 236–249. Accessed April 27, 2025.
https://umj.imath.kiev.ua/index.php/umj/article/view/3449.