@article{CTGDC_1999__40_1_3_0,
     author = {Barr, Michael and Kleisli, Heinrich},
     title = {Topological balls},
     journal = {Cahiers de Topologie et G\'eom\'etrie Diff\'erentielle Cat\'egoriques},
     pages = {3--20},
     year = {1999},
     publisher = {Dunod \'editeur, publi\'e avec le concours du CNRS},
     volume = {40},
     number = {1},
     mrnumber = {1682579},
     zbl = {0922.18004},
     language = {en},
     url = {https://www.numdam.org/item/CTGDC_1999__40_1_3_0/}
}