1. On the mean curvature of submanifolds of euclidean space;Chen, Bang-yen;Bull. Amer. Math. Soc.,1971
2. Rigidity theorems for surfaces in Euclidean space;Chen, Bang-yen;Bull. Amer. Math. Soc. 78 (1972), 72-73; errata, ibid.,1972
3. Surfaces in constant curvature manifolds with parallel mean curvature vector field;Hoffman, David A.;Bull. Amer. Math. Soc.,1972
4. 4. D. A. Hoffman, Surfaces of constant mean curvature in constant curvature manifolds (to appear).
5. 5. H. B. Lawson, Jr., Minimal varieties in constant curvature manifolds, Thesis, Stanford University, Stanford, Calif., 1968.