Complex sentence: Aczél (1966) refers to the "associativity equation" and lists 98 references to works that discuss it or use it, and gives a proof that doesn't require differentiability (pages 256-267).
Split into simpler sentences: Aczél (1966) refers to the "associativity equation" and lists 98 references to works that discuss it or use it. Gives a proof that doesn't require differentiability (pages 256-267).