@article{IM_1995__120_2_144275,
     author = {Christopher B. Croke and Bruce Kleiner},
     title = {On tori without conjugate points.},
     journal = {Inventiones mathematicae},
     pages = {241--258},
     publisher = {mathdoc},
     volume = {120},
     number = {2},
     year = {1995},
     zbl = {0842.53028},
     url = {http://geodesic.mathdoc.fr/item/IM_1995__120_2_144275/}
}