Minimal surface maps, fixed point indices and a Jiang-Guo type inequality Michael Kelly (1999) Banach Center Publications
Multiple perturbed solutions near nondegenerate manifolds of solutions Michal Fečkan (1993) Commentationes Mathematicae Universitatis Carolinae The existence of multiple solutions for perturbed equations is shown near a manifold of solutions of an unperturbed equation via the Nielsen fixed point theory.