1. Nonregular contact structures on Brieskorn manifolds;Abe, Kinetsu;Bull. Amer. Math. Soc.,1975
2. Lecture Notes in Mathematics, Vol. 509;Blair, David E.,1976
3. Lectures on Morse theory, old and new;Bott, Raoul;Bull. Amer. Math. Soc. (N.S.),1982
4. Flots riemanniens;Carrière, Yves;Ast\'{e}risque,1984
5. Invariant submanifolds in a contact Riemannian manifold;Endo, Hiroshi;Tensor (N.S.),1985