I am interested in differential cohomology & secondary characteristic classes and am currently studying the notes by Ulrich Bunke. While these are nice notes, I sometimes find it hard to fill in the gaps in the proofs. Could someone please suggest a reference that I could use to supplement the article ? Are there any other good references on this subject for a beginner ?
As regards my background, I have studied homology and cohomology theory, basic homotopy theory & topology of fibre bundles (from Husemoller's book) and differential geometry (connections, curvature, deRham cohomology, chern classes).
Thanks a lot !