How do I get many magic books quickly and easily in survival mode?
Villages and action
If you enchant a fishing rod with luck of the sea 3 and then you get quite a few enchanting books
Find a village and trade with villagers
Clap the book on the magic table and lapis.
Or you're looking for libraries in Strongholds, where you'll find ultra-awesome books.
Fishing is also possible, as Brainstorm1610 wrote.
Build a bully farm, and just kill monsters, put an enchantment table next to it → done.
As an alternative to farming XP: remove nether quartz
