1. Proceedings of the Steklov Institute of Mathematics, No. 90 (1967);Anosov, D. V.,1969
2. Lecture Notes in Mathematics, No. 35;Bhatia, N. P.,1967
3. P. Eberlein and B. O’Neill, Visibility manifolds (to appear).
4. Geodesic instability;Green, L. W.;Proc. Amer. Math. Soc.,1956
5. Surfaces without conjugate points;Green, L. W.;Trans. Amer. Math. Soc.,1954