@article{JRAM_1992__427_153414,
     author = {P.M. Fitzpatrick and J. Pejsachowicz and P.J. Rabier},
     title = {The degree of proper {C2} {Fredholm} mapppings {I.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {1--34},
     publisher = {mathdoc},
     volume = {427},
     year = {1992},
     zbl = {0745.47049},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1992__427_153414/}
}