reply to r.brown@bangor.ac.uk The paper (R. BROWN and HIGGINS, P.J.), `Cubical abelian groups with connections are equivalent to chain complexes', Homology, Homotopy and Applications, 5(1) (2003) 49-52. has a reference to Grothendieck's `cat\'egorie cofibr\'ee....' (1968) SLNM 79, (the canonical reference for the first question), and also to Bourn (JPAA 1990), and gives a proof that 5 different structures are, in an additive category with kernels, equivalent to chain complexes. Among these structures is strict globular omega-categories. However, this is deduced from some non abelian and more difficult results. Ronnie Brown Dear Categorists - Who first showed that an internal category in the category of abelian groups was a 2-term chain complex of abelian groups? What's a good reference? Who first showed that an internal strict omega-category in the category of abelian groups was a chain complex of abelian groups? What's a good reference? (Of course for "internal X in the category of Y's", I am willing to accept "internal Y in the category of X's" as a substitute.) Best, jb