Cita APA (7a ed.)

Roebuck, K. (2011). Virtual worlds. [s.n.].

Cita Chicago Style (17a ed.)

Roebuck, Kevin. Virtual Worlds. Lexington, Kentucky: [s.n.], 2011.

Cita MLA (9a ed.)

Roebuck, Kevin. Virtual Worlds. [s.n.], 2011.