Cristina, Jan, Tadeusz Iwaniec, Leonid V. Kovalev, and Jani Onninen. 2014. “The Hopf-Laplace Equation: Harmonicity and Regularity”. ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE 13 (4):1145-87. https://doi.org/10.2422/2036-2145.201203_006.