Any time I have the opportunity to collect books I do so. Yesterday one of the offices was being cleaned out. When people retire or change jobs often they leave their library there because they don't expect to use those books any more. I figure anything that will give me more knowledge that will come in handy in a SHTF situation is worth bringing home. Some were government publications, others for the general population. Here's some:
California Forests: Trends, Problems, and Opportunities - I like the chapter on Forest Damaging Agents: fire, insects, diseases, weather damage, animal damage, people caused damage. Those topics give you things to think about even in your own orchard. How can you prevent damage?
Pruning Trees: I can't remember the title but I think that was it. It was a good book because it showed lots of color photos. It also provided photos of damage caused to trees by improperly pruning, but then showed ways to try to correct the damage.
Preliminary Guidelines for Managing California's Hardwood Rangelands: - This one is my favorite. Contents includes Ways to regenerate oaks, Conducting a firewood operation, Is hardwood range management profitable, All about acorns. There's also really good information on the carrying capacity of the land to support cattle and other animals.
While these may not be the exact types of reference materials you are looking for, they provide a good deal of knowledge. Although I can tell you things from my experiences it is nice to be able to get other points of view from subject matter experts.