@article{CTGDC_1988__29_4_255_0,
     author = {Ehresmann, Andr\'ee Charles},
     title = {Trenti\`eme anniversaire},
     journal = {Cahiers de Topologie et G\'eom\'etrie Diff\'erentielle Cat\'egoriques},
     pages = {255--256},
     publisher = {Dunod \'editeur, publi\'e avec le concours du CNRS},
     volume = {29},
     number = {4},
     year = {1988},
     language = {fr},
     url = {http://archive.numdam.org/item/CTGDC_1988__29_4_255_0/}
}