The volumes of stuff this place has compiled in an easy to download PFD format is fantastic. They have done a lot of work and though the downloads are free, I'm sure they take donations of appreciation for their effort. Just the e-books alone: math, science, language, physics, anatomy, medical, military, self-defense, martial arts, firearms, marksmanship, architecture, engineering, masonry, construction, electrical, plumbing, survival, self sufficiency, political, philosophical, and literary classics. I could go on but I think you get the point. Check it out. I've been preparing what I would call a doomsday library; a physical library of knowledge that would facilitate life without access to technology, like internet, hospitals, or grocery stores; if such a situation were to ever occur. Stacks of three ring binders, and a gallon of printer ink later, you've got yourself something.