Erfworld keeps a record of every book ever published. Whenever a side falls, its history is automagically published. It is also possible for a side to publish books on their own with a Signamancer. They pop naturally whenever a library is built or upgraded.
Some books are enchanted into magic items. One example is the Tome of Flintlock, which was enchanted with Signamancy to make it readable and editable only by the true King of Jetstone. Another example is the eyebooks, products of an Eyemancy caster link, which possess the ability to transmit Thinkagrams to one another, record information directly from the user's mind, and project 3D Foolamancy.