Originally published:
Lecture Notes in Mathematics, Volume 80, Springer-Verlag, 1969.
MSC 2000: 18C05, 18C15, 18E25, 18G10
Keywords: Triples, Homology, Equational Categories
Republished in:
Reprints in Theory and Applications of Categories,
No. 18 (2008) pp. 1-303
http://www.tac.mta.ca/tac/reprints/articles/18/tr18.dvi
http://www.tac.mta.ca/tac/reprints/articles/18/tr18.ps
http://www.tac.mta.ca/tac/reprints/articles/18/tr18.pdf