1. Cohomology theories;Brown, Edgar H., Jr.;Ann. of Math. (2),1962
2. The bar construction and abelian 𝐻-spaces;Milgram, R. James;Illinois J. Math.,1967
3. Homotopy associativity of 𝐻-spaces. I, II;Stasheff, James Dillon;Trans. Amer. Math. Soc. 108 (1963), 275-292; ibid.,1963