1. A book for use in an augmented reality system, comprising: a first page on a first leaf of the book comprising a first fiduciary marker for indicating an orientation of the book to a recognition system; a second page on a second leaf of the book comprising a second fiduciary marker and also a page marker for indicating a page number of the second page to the recognition system; wherein: an orientation of the page marker is ambiguous without reference to a fiduciary marker; and the page marker is positioned closer to an edge of the second page than the second fiduciary marker, so as to become visible to the recognition system before the second fiduciary marker as the book is turned to the second page.