[1] CANTWELL John:
Topological non-degenerate functions. Tohoku Mathematical Journal 20 (1965), 120-125.
MR 0232397
[2] MORSE Marston:
The existence of polar non-degenerate functions on differentiable manifolds. Annals of Mathematics 71 (1960), 352-383.
MR 0113232 |
Zbl 0096.03604
[3] MORSE Marston:
Topologically non-degenerate functions on a compact n-manifold M. Journal d'Analyse Math. 7 (1959), 189-208.
MR 0113233 |
Zbl 0096.30603