1. [1] Defever, F.; Deszcz, R.; Verstraelen, L. and Yaprak,S., Pseudosymmetry type curvature
properties of hypersurfaces, Proceedings of the Conferences on Differential Geometry and Vision,
Theory of Submanifolds, (1992), 109-131.
2. [2] Delanoe, Ph., Remarques sur les vari´et´es localement hessiennes, Osaka J. Math. 26 (1989),
65-69.
3. [3] Duggal, Krishan L. and Bejancu, A., Lightlike Submanifolds of Semi-Riemannian Manifolds and
Applications, Kluwer Academic Publishers, Dordrecht, 1996.
4. [4] Koszul, J.L, Vari´et´es locament plates et convexit´e, Osaka J. Math. 2 (1965), 285-290.
5. [5] Koszul, J.L, D´eformations des connexions localement plates, Ann.Inst.Fourrier 18
(1968),103-114.