Thelin, Francois de, y J. Velin. «Existence and Nonexistence of Nontrivíal Solutions for Some Nonlinear Elliptie Systems». Revista Matemática Complutense 6, no. 1 (enero 1, 1993): 153. https://doi.org/10.5209/rev_REMA.1993.v6.n1.17864.