Cita APA (7a ed.)

Unruh, D. (1979). Characteristics and types of participation in social worlds. [s.n.].

Cita Chicago Style (17a ed.)

Unruh, David. Characteristics and Types of Participation in Social Worlds. [S.l.]: [s.n.], 1979.

Cita MLA (9a ed.)

Unruh, David. Characteristics and Types of Participation in Social Worlds. [s.n.], 1979.