I don't think this attribution makes sense without some further qualification. There is diagram chasing ten years earlier in Cartan-Eilenberg's Homological Algebra (1955) -- they prove the five lemma early on -- and Mac…
I don't think this attribution makes sense without some further qualification. There is diagram chasing ten years earlier in Cartan-Eilenberg's Homological Algebra (1955) -- they prove the five lemma early on -- and Mac…