Mel'nik, V. S. “Multivariational Inequalities and Operator Inclusions in Banach Spaces With Mappings of the Class $(S)_{+}$”. Ukrains’kyi Matematychnyi Zhurnal 52, no. 11 (November 25, 2000): 1513–1523. Accessed December 5, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/4557.