@article{CTGDC_1972__13_2_104_0,
     author = {Bastiani, Andr\'ee and Ehresmann, Charles},
     title = {Categories of sketched structures},
     journal = {Cahiers de topologie et g\'eom\'etrie diff\'erentielle},
     pages = {104--214},
     publisher = {Dunod \'editeur, publi\'e avec le concours du CNRS},
     volume = {13},
     number = {2},
     year = {1972},
     mrnumber = {323856},
     zbl = {0263.18009},
     language = {en},
     url = {http://www.numdam.org/item/CTGDC_1972__13_2_104_0/}
}