APA-referens (7:e uppl.)

Preston, R. (1982). Teaching world understanding. Prentice-Hall.

Chicago-referens (17:e uppl.)

Preston, Ralph. Teaching World Understanding. New yark: Prentice-Hall, 1982.

MLA-referens (9:e uppl.)

Preston, Ralph. Teaching World Understanding. Prentice-Hall, 1982.