APA (7th ed.) Zitazioa

Agricultural Resources & Environmental Indicators. United States Department of Agriculture.

Chicago Style (17th ed.) Zitazioa

Agricultural Resources & Environmental Indicators. United States Department of Agriculture.

MLA (9th ed.) Zitazioa

Agricultural Resources & Environmental Indicators. United States Department of Agriculture.

Kontuz: berrikusi erreferentzia hauek erabili aurretik.