W. Robinson, Deerk, and Adam Sikora. “Markov Uniqueness of Degenerate Elliptic Operators”. ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE 10, no. 3 (October 5, 2011): 683-710. Accessed May 29, 2025. http://20.103.181.36/index.php/annaliscienze/article/view/245.