Principles, Cases, and Materials is an openly-licensed antitrust law textbook, co-authored by Profs. Daniel Francis and Christopher Jon Sprigman (both teach at the New York University School of Law). The textbook is made available under a Creative Commons Attribution-NonCommercial-Share Alike 4.0 International License. Under the terms of this license, you are free to copy, modify, and redistribute the textbook in part or whole in any format provided that (1) you do so only for non-commercial purposes, and (2) you comply with the attribution principles of the license (credit the authors, link to the license, and, if you make modifications, share them under the same license terms).
Worst organization. What a waste of potential for a fascinating topic. This book gets a second star because the cover has a man fighting a horse, which I don't understand but think is pretty neat.