Martio, Olli. “Quasiminimizing Properties of Solutions to Riccati Type Equations”. ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE 12, no. 4 (December 19, 2013): 823-832. Accessed May 27, 2025. http://20.103.181.36/index.php/annaliscienze/article/view/312.