For nearly one hundred years, The Chicago Manual of Style has been the authoritative reference for writers, editors, and publishers. Now in its fifteenth edition, the Manual has been thoroughly revised and updated. The chapter on indexing presented here has been reorganized, streamlined, and revised for the electronic age. It provides examples and recommendations on style and method for professionals, authors, and others who prepare indexes for published works.
This is what my prof recommended us to read as an assignment. As a non-indexer, I actually find the book understandable without getting confused with some jargons. It's simple and I learned many things from it.