Matthews, W. H. The Geologic Story of Palo Duro Canyon.
Chicago-čujuhus (17. p.)Matthews, William Henry. The Geologic Story of Palo Duro Canyon.
MLA-čujuhus (9. p.)Matthews, William Henry. The Geologic Story of Palo Duro Canyon.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.