I found this one at random in my favorite used bookshop last week. Had never heard of it before, but it’s really neato—Cage’s lectures, notes, letters, etc. on a range of subjects, including Charles Ives, Marcel Duchamp, and making the world better. Cover’s in rough shape, but it’s a first edition paperback, so all’s well &c.
A few pics from the strange interior (no worries, I will be plundering the book for posts in the months to come):