@article{CM_1984__52_3_275_0,
     author = {Brin, M. and Karcher, H.},
     title = {Frame flows on manifolds with pinched negative curvature},
     journal = {Compositio Mathematica},
     pages = {275--297},
     publisher = {Martinus Nijhoff Publishers},
     volume = {52},
     number = {3},
     year = {1984},
     mrnumber = {756723},
     zbl = {0561.58039},
     language = {en},
     url = {http://archive.numdam.org/item/CM_1984__52_3_275_0/}
}