Fang, Ming-Lei, et al. “EXISTENCE OF THREE SOLUTIONS FOR NONLOCAL ELLIPTIC SYSTEM OF (p\(_1\) , . , p\(_n\))-KIRCHHOFF TYPE”. Italian Journal of Pure and Applied Mathematics, vol. 33, Dec. 2014, pp. 489-00, https://journals.uniurb.it/index.php/ijpam/article/view/6273.