Closed Nodal Lines and Interior Hot Spots of the Second Eigenfunctions of the Laplacian on Surfaces Pedro Freitas 35P0558J5035P15eigenfunctionsnodal lineshot spots Indiana University Mathematics Journal 2002 text pdf 10.1512/iumj.2002.51.2208 10.1512/iumj.2002.51.2208 en Indiana Univ. Math. J. 51 (2002) 305 - 316 state-of-the-art mathematics http://iumj.org/access/