Ehresmann's theorem

年，介紹了纖維叢的概念（獨立於哈斯勒·惠特尼與諾曼·斯廷羅德）。 埃雷斯曼定理（Ehresmann's theorem（英语：Ehresmann's theorem）） 埃雷斯曼联络 `The mathematical legacy of Charles Ehresmann', Proceedings of the 7th Conference

groupoids in group theory, for example to a generalisation of Grushko's theorem, and in topology, e.g. fundamental groupoid. Mackenzie, K. C. H., 2005