DiBenedetto, Emmanuele, Ugo Gianazza, and Vincenzo Vespri. “Forward, Backward and Elliptic Harnack Inequalities for Non-Negative Solutions to Certain Singular Parabolic Partial Differential Equations”. ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE 9, no. 2 (June 9, 2010): 385-422. Accessed May 27, 2025. http://20.103.181.36/index.php/annaliscienze/article/view/208.