Freeman, J. F. (2008). High Plains horticulture: A history. University Press of Colorado.
Lua i Stíl Chicago (17ú heag.)Freeman, John F. High Plains Horticulture: A History. Boulder: University Press of Colorado, 2008.
Lua MLA (9ú heag.)Freeman, John F. High Plains Horticulture: A History. University Press of Colorado, 2008.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.