The Aionomica, otherwise known as the Sacred Jedi texts.
Books, defined as printed works with bound pages, were not commonly found within the Galactic Empire. The preference leaned towards alternative storage methods, including data-tapes and flimsiplast. When Agent Kallus entered the office of Captain Zataire aboard the Lawbringer, he was taken aback by the sight of a bookshelf. Beru Whitesun Lars engaged in reading storybooks aloud to her nephew, Luke Skywalker. During the time of the Galactic Civil War, the White Book, a field manual that provided the rules and procedures established by Alliance High Command, was used by the Alliance to Restore the Republic. The collection of Jedi texts on Ahch-To in 34 ABY were known as the Sacred Jedi texts.
The idea that physical books were a rarity in the Star Wars galaxy was first presented in the Expanded Universe, specifically in works such as The New Jedi Order: Force Heretic II: Refugee. Even though these stories are now part of the Star Wars Legends timeline and are no longer considered canon, the concept of printed books being uncommon has persisted in the current continuity.