I typically read and watch everything I can, and I notice that the foundational concepts are similar in many of them. Beyond that, and now that the fundamentals have become second nature, I am looking for that one ingenious tidbit or tip or insight. It seems like many authors have at least one thing to share that is unique and those are the gems.
I don't have a specific book to recommend, but I read through every one I find looking for those gems. The most important skill is reading the sign, and learning to trust your interpretation of what you see. I ran a lot of video cams on beaver locations for years, and eventually I realized that beaver leave a lot of sign, and I trust my ability to read what I am seeing and apply my toolkit to the task at hand. The cameras did help me train my eye to see and interpret the sign.
There is also an important distinction between beaver control work and fur trapping. The goals are different and sometimes the legal equipment is different. So when looking for books, and when studying them, keep in mind that most are focused on fur trapping where running a lot of equipment fast and getting the “easy” ones with the least amount of time and effort is the goal. When doing control work, it is more of a “chess game” where your goal is to get the ones causing the problem, and that is more of a careful calculated approach for many reasons and in most situations, and especially the last few trouble makers in a colony. I have at times spent an hour in the shop making a special tool just be able to exploit a particular situation to get a single beaver. I would not do that in numbers fur trapping, the economics just would not be worth the trouble.