Medvid’, I. M. “Higher-Order Parabolic Variational Inequality in Unbounded Domains”. Ukrains’kyi Matematychnyi Zhurnal 60, no. 7 (July 25, 2008): 949–968. Accessed December 5, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/3211.