Abstract: A manual (1) comprising a binder (6) and pages (3) releasably retained in the binder (6) comprises apparatus (2) for identifying an opened page (3) and for transmitting the identity of the page (3) to a computer (4). The apparatus (2) comprises a carrier member (15) which carries a plurality of photo sensors (16) for reading a binary identity code (17) along an edge of each page (3) for identifying the page. A plurality of input keys (37) on the carrier member (15) carry identifying symbols (40) which correspond to identifying symbols (41) provided on the pages (3) adjacent passages of text for facilitating inputting of select signals for operating the computer (4) to display additional data on a visual display unit (5) relating to the passage identified by the corresponding identifying symbol.