@article{SE_1964__6__A9_0,
     author = {Ehresmann, Charles},
     title = {Prolongements des cat\'egories diff\'erentiables},
     journal = {S\'eminaire Ehresmann. Topologie et g\'eom\'etrie diff\'erentielle},
     note = {talk:9},
     pages = {1--8},
     publisher = {Secr\'etariat math\'ematique},
     volume = {6},
     year = {1964},
     mrnumber = {179225},
     zbl = {0192.10102},
     language = {fr},
     url = {http://www.numdam.org/item/SE_1964__6__A9_0/}
}