Long, Wei, and Shuangjie Peng. “Multiple Positive Solutions for a Type of Nonlinear Schrödinger Equations”. ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE 16, no. 2 (June 28, 2016): 603-623. Accessed May 27, 2025. http://20.103.181.36/index.php/annaliscienze/article/view/459.