The Mezzotint
This is probably the definitive guide to the history and process of mezzotint printing. There are tons of images and the technical information is exhaustive. If you want to learn how to make mezzotints, this is your best resource. Unfortunately, the actual history of the process is not terribly interesting. It’s mostly a laundry list of various publishers who were focused on copying others’ work rather than exploring the process on its own merits.
Cool story: I own a copy of one of Carol Wax’s mezzotint prints entitled Remington Striptease.