Preston, R. (1982). Teaching world understanding. Prentice-Hall.
Chicago-čujuhus (17. p.)Preston, Ralph. Teaching World Understanding. New yark: Prentice-Hall, 1982.
MLA-čujuhus (9. p.)Preston, Ralph. Teaching World Understanding. Prentice-Hall, 1982.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.