I don't pack survival books when I travel or go backpacking (unfortunately, it's been quite a while since I went on any backpacking trip of note). I read them books ahead of time. Although I'll admit, sometimes in the past I have thrown in that small sized GEM short version book of the SAS Survival Manual. Not for learning while out there, more as a memory refresher for the bigger original book. Things like the finer points of how to create various trigger mechanisms for snares would normally escape my memory, since I've never had to do that in real life. So the GEM book would be good reminders for that, if necessary.

My favorites have already been mentioned: The SAS Survival Manual, and Cody Lundins book. The GEM book is on the list too, for its "reminder" properties.