WANG, Q.; XIA, C. Universal bounds for eigenvalues of Schrödinger operator on Riemannian manifolds. Annales Fennici Mathematici, [S. l.], v. 33, n. 2, p. 319–336, 2008. Disponível em: https://afm.journal.fi/article/view/135235. Acesso em: 19 may. 2024.