@article{SE_1960-1962__3__A4_0,
     author = {Ehresmann, Charles},
     title = {Esp\`eces de structures locales},
     journal = {S\'eminaire Ehresmann. Topologie et g\'eom\'etrie diff\'erentielle},
     publisher = {Secr\'etariat math\'ematique},
     volume = {3},
     year = {1960-1962},
     note = {talk:4},
     zbl = {0106.36302},
     language = {fr},
     url = {http://www.numdam.org/item/SE_1960-1962__3__A4_0}
}

Ehresmann, Charles. Espèces de structures locales. Séminaire Ehresmann. Topologie et géométrie différentielle, Volume 3 (1960-1962) , Talk no. 4, 24 p. http://www.numdam.org/item/SE_1960-1962__3__A4_0/