@article{AFST_1998_6_7_3_365_0,
     author = {Blair, David E.},
     title = {Special directions on contact metric manifolds of negative $\xi $-sectional curvature},
     journal = {Annales de la Facult\'e des sciences de Toulouse : Math\'ematiques},
     pages = {365--378},
     publisher = {Universit\'e Paul Sabatier. Facult\'e des sciences},
     address = {Toulouse},
     volume = {Ser. 6, 7},
     number = {3},
     year = {1998},
     zbl = {0918.53012},
     language = {en},
     url = {http://archive.numdam.org/item/AFST_1998_6_7_3_365_0/}
}