Surjectivity Results for Non-linear Mappings from a Banach Space to It's Dual. P.M. Fitzpatrick — 1973 Mathematische Annalen
Global Several-Parameter Bifurcation and Continuation Theorems: a UnifiedApproach Via Complementing Maps. P.M. Fitzpatrick; I. Massabò; J. Pejsachowicz — 1983 Mathematische Annalen
The degree of proper C2 Fredholm mapppings I. P.M. Fitzpatrick; J. Pejsachowicz; P.J. Rabier — 1992 Journal für die reine und angewandte Mathematik