Algebraic & Geometric Topology Volume 2, issue 1 (2002)

1	A Dold, Die geometrische Realisierung eines schiefen kartesischen Produktes., Arch. Math. 9 (1958) 275 MR0105110
2	Z Fiedorowicz, Classifying spaces of topological monoids and categories, Amer. J. Math. 106 (1984) 301 MR737777
3	D McDuff, On the classifying spaces of discrete monoids, Topology 18 (1979) 313 MR551013
4	D Puppe, A theorem on semi-simplicial monoid complexes, Ann. of Math. $(2)$ 70 (1959) 379 MR0123321