person
Riva, Giuseppe, John A. Waterworth and Eva L. Waterworth. 2004. The Layers of Presence: A Bio–cultural Approach to Understanding Presence in Natural and Mediated Environments. In CyberPsychology & Behavior (7) 4: 402–416.
IJsselsteijn, Wijnand and Giuseppe Riva. 2003. Being There, The experience of presence in mediated environments. In Being there: Concepts, effects and measurement of user experience in synthetic environments, ed. Giuseppe Riva, Fabrizio Davide, Wijnand IJsselsteijn, 3-16. Amsterdam: IOS Press. Retrieved from
http:/www.ijsselstein.nl (accessed 30 november, 2006)