I was thinking paper degrades so if you want to keep them for reference or to teach in the future keeping them safe in airtight containers would be the safe way.
Yeah you mentioned Kindle and thought, hmmmmmm until it got fried or something. I like the library idea, yes reading and learning things now is good, but I always reference materials if it has been awhile. I have always been a jack of all trades, learn fast. I like to take things apart, read and study them until I am comfortable with the knowledge.