Παραπομπή σε μορφή APA (7η εκδ.)

Harding, P. E. (1991). Foliar nutrient level studies in smallholder coffee gardens in the Kainantu area of Papua New Guinea. PNG Coffee research Institute.

Παραπομπή σε μορφή Chicago (17η εκδ.)

Harding, Paul E. Foliar Nutrient Level Studies in Smallholder Coffee Gardens in the Kainantu Area of Papua New Guinea. PNG Coffee research Institute, 1991.

Παραπομπή σε μορφή MLA (9th εκδ.)

Harding, Paul E. Foliar Nutrient Level Studies in Smallholder Coffee Gardens in the Kainantu Area of Papua New Guinea. PNG Coffee research Institute, 1991.