Zorii, N. V. “A Noncompact Variational Problem in the Theory of Riesz Potentials. II”. Ukrains’kyi Matematychnyi Zhurnal 48, no. 5 (May 25, 1996): 603–613. Accessed April 27, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/5293.