Lavrenyuk, S. P., and M. B. Ptashnik. “Pseudoparabolic Variational Inequalities Without Initial Conditions”.
Ukrains’kyi Matematychnyi Zhurnal 50, no. 7 (July 25, 1998): 919–929. Accessed April 11, 2025.
https://umj.imath.kiev.ua/index.php/umj/article/view/4872.