APA-Zitierstil (7. Ausg.)

Spencer, D. C. (1980). Thinking about open learning systems. [s.n.].

Chicago-Zitierstil (17. Ausg.)

Spencer, Douglas C. Thinking About Open Learning Systems. London: [s.n.], 1980.

MLA-Zitierstil (9. Ausg.)

Spencer, Douglas C. Thinking About Open Learning Systems. [s.n.], 1980.