@article{GDZPPN002216906,
title = {Stability of Critical Points under Small Perturbations. Part I: Topological Theory.},
journal = {Manuscripta mathematica},
volume = {7},
year = {1972},
pages = {387-411},
zbl = {0244.58001},
url = {http://dml.mathdoc.fr/item/GDZPPN002216906}
}
Reeken, Michael. Stability of Critical Points under Small Perturbations. Part I: Topological Theory.. Manuscripta mathematica, Tome 7 (1972) pp. 387-411. http://gdmltest.u-ga.fr/item/GDZPPN002216906/