Wallen, R. N. (1992). Introduction to physical geography. WM C. Brown.
Chicago-čujuhus (17. p.)Wallen, Robert N. Introduction to Physical Geography. Boulevard: WM C. Brown, 1992.
MLA-čujuhus (9. p.)Wallen, Robert N. Introduction to Physical Geography. WM C. Brown, 1992.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.