Foster, R. J. (1997). Physical Geology (18th ed.). Charles E. Merrill.
Chicago-čujuhus (17. p.)Foster, Robert J. Physical Geology. 18th ed. Columbus: Charles E. Merrill, 1997.
MLA-čujuhus (9. p.)Foster, Robert J. Physical Geology. 18th ed. Charles E. Merrill, 1997.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.