Ah, United We Fall, by the late, great Pat Works. I still have my well-worn copy. Back in the day, even before my time, he used to put out a newsletter called the RWunderground, and I believe UWF is an anthology from that. How recently and where did you find it? He also had another great book, The Art of Freefall Relative Work. I lost my copy of that many years ago when I gave it to an up-and-coming student and never got it back. Hopefully they did the same. I, for one, would absolutely still recommend these timeless works for anyone interested in skydiving and it's history.
Perhaps someone could convince Jan to re-issue them.