I've read everything I can lay hands on including borrowing some stuff long out of print.
I'd suggest 4 books
Abominable Snowmen - Legend Comes to Life by Ivan Sanderson
Sasquatch: Legend Meets Science by Jeff Meldrum - get the book and the DVD.
The Locals by Thom Powell
Enoch by Autumn Williams
These, while not exhaustive, provide a consistent context for what I've been running into out there, consistent with what witnesses are reporting, but lack presentation of the overarching theme that brings them all together. That book remains unwritten so for now, you'll have to put the pieces together for yourself. That may or may not be ok for you, some people like to be spoon fed, others, like me, like a little sweat-equity in our "ah-hah" moments.
Many other books regurgitate long lists of accounts, some famous, some obscure, but none of those, individually, give you WHY, they just give you HOW OFTEN.
There is another aspect which you have to be somewhat conversant in to understand the complete picture. That's what we refer to as "the woo". There is not a single best book for getting a cross-section. Many people like Jack "Keuwaunee" Lapseritis' writings. I do not. I think he is a fraud and worse. Instead, I recommend Teluke A Bigfoot Account by White Song Eagle and Valley of the Skookum by Sali Shepard-Wolford. Some aspects are addressed by Thom Powell in his book I list above. Frankly, I don't have answers, but the questions raised appear to be real, and, because they repeat apparently independently, are just as worthy of careful scientific study (which does not include scoffing or dismissal) as the topic of bigfoot itself.
MIB