1. R. Abraham, J. E. Marsden and T. Ratiu, Manifolds, tensor analysis and applications, Second edition, Applied Mathematical Sciences 75, Springer-Verlag, New York, 1988.
2. D. E. Blair, Riemannian geometry of contact and symplectic manifolds, Second edition, Progress in Mathematics 203, Birkhäuser, Boston, 2010.
3. F. J. E. Dillen and L. C. A. Verstraelen, Handbook of differential geometry, Volume II, North-Holland, Amsterdam, 2006.
4. I. Hasegawa, A note on hypersurfaces in a Sasakian space form, J. Hokkaido Univ. Ed. Sect. II A 41 (1990), 1-9.
5. C. D. Hill and M. Nacinovich, A necessary condition for global Stein immersion of compact CR-manifolds, Riv. Mat. Univ. Parma 1 (1992), 175-182.