Bigfoot in Maine is a great book - it benefits from the author's ability to gain the confidence of witnesses and let them tell their story, adding details that weren't common knowledge to well-publicized cases like the Durham Gorilla. 5 stars.*
I'm going to go out on a limb and state that When Roger Met Patty is the most important book on the PG film, as it persuasively demonstrates why the film could not have been faked and does so with technical knowledge of film, cameras, make-up, etc., that few people possess. 6 stars.* Contrast that with The Making of Bigfoot by Greg Long, which in my opinion can be summarized as, "these people are beneath me, I don't like them, and therefore they are frauds."
Sasquatch: Legend Meets Science is a good introductory book.
Lastly, I highly recommend The Sasquatch Hunter's Field Manual, by our very own Hiflier. It is a very good book condensing much of what he has written here and it is well-written. I'm grateful to have a signed copy.
* I am not related to, friends of (except for Hiflier), or compensated by the authors.