Open covers and infinitary operations in C ∞ -rings
Cahiers de Topologie et Géométrie Différentielle Catégoriques, Volume 22 (1981) no. 3, p. 287-300 
@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 Cat\'egoriques},
     publisher = {Dunod \'editeur, publi\'e avec le concours du CNRS},
     volume = {22},
     number = {3},
     year = {1981},
     pages = {287-300},
     zbl = {0472.18008},
     language = {en},
     url = {http://www.numdam.org/item/CTGDC_1981__22_3_287_0}
}

Dubuc, Eduardo J. Open covers and infinitary operations in $C^\infty $-rings. Cahiers de Topologie et Géométrie Différentielle Catégoriques, Volume 22 (1981) no. 3, pp. 287-300. http://www.numdam.org/item/CTGDC_1981__22_3_287_0/

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