On branched covers in topos theory. Funk, Jonathon (2000) Theory and Applications of Categories [electronic only]
On the relations between abstract and geometrical equivalence of abstract objects Mieczysław Kucharzewski, Brunon Szociński, Marek Żabka (1990) Annales Polonici Mathematici
On Yetter's invariant and an extension of the Dijkgraaf-Witten invariant to categorical groups. Martins, Joao Faria, Porter, Timothy (2007) Theory and Applications of Categories [electronic only]
Operads in higher-dimensional category theory. Leinster, Tom (2004) Theory and Applications of Categories [electronic only]