Negotiating presence-in-absence: contact, content and context. - Steve Howard; Jesper Kjeldskov; Mikael B. Skov; Kasper Garnæs; Olga Grünberger (CHI, 2006)

Designing technologies for presence-in-absence: illustrating the Cube and the Picture Frame. - Kasper Garnæs; Olga Grünberger; Jesper Kjeldskov; Mikael B. Skov (Pers. Ubiquitous Comput., 2007)