@article{CTGDC_1967__9_4_389_0,
     author = {Bonan, Edmond},
     title = {Sur les $G$-structures de type quaternionien},
     journal = {Cahiers de topologie et g\'eom\'etrie diff\'erentielle},
     pages = {389--463},
     publisher = {Dunod \'editeur, publi\'e avec le concours du CNRS},
     volume = {9},
     number = {4},
     year = {1967},
     mrnumber = {233302},
     zbl = {0171.20802},
     language = {fr},
     url = {http://www.numdam.org/item/CTGDC_1967__9_4_389_0/}
}