Kalita, E. A. “Morrey Regularity of Solutions of Nonlinear Elliptic Systems of Arbitrary Order With Restrictions on the Modulus of Ellipticity”. Ukrains’kyi Matematychnyi Zhurnal 54, no. 11 (November 25, 2002): 1452–1466. Accessed April 27, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/4184.