@article{CTGDC_1981__22_1_45_0,
     author = {Keigher, William F.},
     title = {Differential algebra in a topos},
     journal = {Cahiers de topologie et g\'eom\'etrie diff\'erentielle},
     pages = {45--51},
     year = {1981},
     publisher = {Dunod \'editeur, publi\'e avec le concours du CNRS},
     volume = {22},
     number = {1},
     mrnumber = {609158},
     zbl = {0459.18004},
     language = {en},
     url = {https://www.numdam.org/item/CTGDC_1981__22_1_45_0/}
}