1. Central extensions of precrossed modules;Arias;Appl. Categ. Structures,2004
2. Exact categories;Barr,1971
3. Homology and standard constructions;Barr,1969
4. Mal’cev, protomodular, homological and semi-abelian categories;Borceux,2004
5. Topological semi-abelian algebras;Borceux;Adv. Math.,2005