1. R.K. Dennis, In search of new "homology" functors having a close relationship to K-theory, preprint, Cornell, 1976.
2. J. Huebschmann, The first k-invariant, Quillen’s space BG+ and the construction of Kan and Thurston, Comm.Math.Helv. 55 (1980), 314–318.
3. J. Milnor, Introduction to Algebraic K-theory, Annals of Mathematics Studies Number 72, Princeton University Press 1971.
4. Lecture Notes in Mathematics;U. Stammbach,1973
5. J.B. Wagoner, Delooping classifying spaces in algebraic K-theory, Top.11 (1972), 349–370.