S. Case, Jeffrey, and A. Rod Gover. “The P’-Operator, the Q’-Curvature, and the CR Tractor Calculus ”. ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE 20, no. 2 (May 19, 2020): 565-618. Accessed June 7, 2025. http://20.103.181.36/index.php/annaliscienze/article/view/686.