Boardman J.M., Vogt R.M. Homotopy Invariant Algebraic Structures on Topological Spaces

Springer-Verlag, 1973. — 257 p. — (Lecture Notes in Mathematics).Introduction.
Motivation and a historical survey.
Topological-algebraic theories.
The bar construction for theories.
Homotopy homomorphisms.
Structures on based spaces.
Iterated loop spaces and actions on classifying spaces.
Homotopy collmits.
Appendix.