Cristina J, Iwaniec T, V. Kovalev L, Onninen J. The Hopf-Laplace equation: harmonicity and regularity. Annali Scienze [Internet]. 2014Dec.23 [cited 2025May27];13(4):1145-87. Available from: http://20.103.181.36/index.php/annaliscienze/article/view/367