00411nam a2200145Ia 4500020001500000082001700015100002100032245005000053260003500103300002600138490002700164500006400191500000500255700000500260  a0817652426  a516bB192.LS  aBallmann, Werner  aLectures on spaces of nonpositive curvatureb  aBaselbBirkhauser Verlagc1995  av, 112p. Bibl. Index.  aDMV Seminar band v 25  aWith an appendix by Misha Brin Ergodicity of Geodesic Flows  a  a