1. [1] Chen, B.-Y.: On the total absolute curvature of manifolds immersed in Riemannian manifold. Kodai Math. Sem. Rep. 19, 299–311 (1967).
2. [2] Chen, B.-Y.: Some integral formulas of the Gauss-Kronecker curvature. Kodai Math. Sem. Rep. 20, 410–413 (1968).
3. [3] Chen, B.-Y.: Notes on the G-Gauss-Kronecker curvature. Nanta Math. 2, 47–53 (1968).
4. [4] Chen, B.-Y.: On the G-total curvature and topology of immersed manifolds. Thesis (Ph.D.)-University of Notre Dame (1970).
5. [5] Chen, B.-Y.: On the total curvature of immersed manifolds. I. An inequality of Fenchel-Borsuk-Willmore. Amer. J. Math. 93, 148–162 (1971).