On the Structure of Solutions of Non-Linear Eigenvalue Problems E. Dancer Indiana University Mathematics Journal 1974 text pdf 10.1512/iumj.1974.23.23087 10.1512/iumj.1974.23.23087 en Indiana Univ. Math. J. 23 (1974) 1069 - 1076 state-of-the-art mathematics http://iumj.org/access/