@article{CTGDC_2008__49_2_142_0,
     author = {Ehresmann, Andr\'ee C.},
     title = {Fifty years of research},
     journal = {Cahiers de Topologie et G\'eom\'etrie Diff\'erentielle Cat\'egoriques},
     pages = {142--152},
     publisher = {Dunod \'editeur, publi\'e avec le concours du CNRS},
     volume = {49},
     number = {2},
     year = {2008},
     mrnumber = {2426400},
     zbl = {1147.01320},
     language = {en},
     url = {http://www.numdam.org/item/CTGDC_2008__49_2_142_0/}
}