@article{CTGDC_1981__22_3_287_0,
     author = {Dubuc, Eduardo J.},
     title = {Open covers and infinitary operations in $C^\infty $-rings},
     journal = {Cahiers de topologie et g\'eom\'etrie diff\'erentielle},
     pages = {287--300},
     publisher = {Dunod \'editeur, publi\'e avec le concours du CNRS},
     volume = {22},
     number = {3},
     year = {1981},
     zbl = {0472.18008},
     language = {en},
     url = {http://www.numdam.org/item/CTGDC_1981__22_3_287_0/}
}