Cita APA (7a ed.)

Garrison, D. R. (1989). Understanding distance education: A framework for the future. Routledge.

Cita Chicago Style (17a ed.)

Garrison, D. R. Understanding Distance Education: A Framework for the Future. London ; New York: Routledge, 1989.

Cita MLA (9a ed.)

Garrison, D. R. Understanding Distance Education: A Framework for the Future. Routledge, 1989.