G. Chiossi, Simon, and Paul-Andi Nagy. “Systems of Symplectic Forms on Four-Manifolds”. ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE 12, no. 3 (September 24, 2013): 717-734. Accessed May 28, 2025. http://20.103.181.36/index.php/annaliscienze/article/view/308.