ZadorozhnaN. M., and PtashnikB. I. “Nonlocal Boundary-Value Problem for Parabolic Equations With Variable Coefficients”. Ukrains’kyi Matematychnyi Zhurnal 47, no. 7 (July 25, 1995): 915–921. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5485.