Schorr, Angela (2003). "Interactivity: The New Media Use Option—State of the Art". In Schorr, Angela; Schenk, Michael; Campbell, William (eds.). Communication Research and Media Science in Europe: Perspectives for Research and Academic Training in Europe's Changing Media Reality. Mouton de Gruyter. p. 57. ISBN978-3-11-017216-4. OCLC954099068. Retrieved 23 April 2017 – via Google Books.
Schorr, Angela (2003). "Interactivity: The New Media Use Option—State of the Art". In Schorr, Angela; Schenk, Michael; Campbell, William (eds.). Communication Research and Media Science in Europe: Perspectives for Research and Academic Training in Europe's Changing Media Reality. Mouton de Gruyter. p. 57. ISBN978-3-11-017216-4. OCLC954099068. Retrieved 23 April 2017 – via Google Books.