@article{MAN_1974__210_162627,
     author = {Y\^otar\^o Tsukamoto},
     title = {On the {Total} {Absolute} {Curvature} of {Closed} {Curves} in {Manifolds} of {Negative} {Curvature.}},
     journal = {Mathematische Annalen},
     pages = {313--320},
     publisher = {mathdoc},
     volume = {210},
     year = {1974},
     zbl = {0273.53033},
     url = {http://geodesic.mathdoc.fr/item/MAN_1974__210_162627/}
}