Nacinovich, Mauro, and Egmont Porten. “ $\mathcal{C}^{\infty}$-Hypoellipticity and Extension of CR Functions”. ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE 14, no. 3 (September 11, 2015): 677-703. Accessed May 27, 2025. http://20.103.181.36/index.php/annaliscienze/article/view/390.