A system for displaying audio content with text including a book holder
and a book. The book holder identifies which book of a plurality is
placed in the holder by detecting magnetic indicators in specific
locations and arrangements which are unique to each book. The page of the
book which a user views at any given time is identified by detection of
ambient light, by detection of a number of circuit elements in parallel,
by detection of progressively stacked magnetic sensors, or by microwave
reflection.