Παραπομπή σε μορφή APA (7η εκδ.)

Ruddle, K. (1974). The Yukpa cultivation system: A study of shifting cultivation in Colombia and Venezuela. University of California Press.

Παραπομπή σε μορφή Chicago (17η εκδ.)

Ruddle, Kenneth. The Yukpa Cultivation System: A Study of Shifting Cultivation in Colombia and Venezuela. Berkeley: University of California Press, 1974.

Παραπομπή σε μορφή MLA (9th εκδ.)

Ruddle, Kenneth. The Yukpa Cultivation System: A Study of Shifting Cultivation in Colombia and Venezuela. University of California Press, 1974.