Minecraft wiki entry for Box_of_Infinite_Books, associated text: The random books are tied to the block such that using the same block multiple times always returns an identical book. The title of the random books given by the block is correlated with the location of the block. The title's pattern takes the format <chunk X>/<chunk Z>/<block orientation>/<distance to the chunk's edge to the right of the block>/<block Y>, so books from the same block always has the same title and content.