@article{GT_2009_13_2_a1,
     author = {Elsner, Tomasz},
     title = {Flats and the flat torus theorem in systolic spaces},
     journal = {Geometry & topology},
     pages = {661--698},
     publisher = {mathdoc},
     volume = {13},
     number = {2},
     year = {2009},
     doi = {10.2140/gt.2009.13.661},
     url = {http://geodesic.mathdoc.fr/articles/10.2140/gt.2009.13.661/}
}