@article{GDZPPN002209470,
title = {The degree of proper C2 Fredholm mapppings I.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {426},
year = {1992},
pages = {1-34},
zbl = {0745.47049},
url = {http://dml.mathdoc.fr/item/GDZPPN002209470}
}
Fitzpatrick, P.M.; Pejsachowicz, J.; Rabier, P.J. The degree of proper C2 Fredholm mapppings I.. Journal für die reine und angewandte Mathematik, Tome 426 (1992) pp. 1-34. http://gdmltest.u-ga.fr/item/GDZPPN002209470/