Cooper, G. P. a. R. (1931). The Evergreen Forests of Liberia.: A report on investigation made in the west african republic of liberia by the yale university school of forestry in cooperation with the firestone plantations company. Yale University.
Παραπομπή σε μορφή Chicago (17η εκδ.)Cooper, G. Proctor and Recorc. The Evergreen Forests of Liberia.: A Report on Investigation Made in the West African Republic of Liberia by the Yale University School of Forestry in Cooperation with the Firestone Plantations Company. New Haven: Yale University, 1931.
Παραπομπή σε μορφή MLA (9th εκδ.)Cooper, G. Proctor and Recorc. The Evergreen Forests of Liberia.: A Report on Investigation Made in the West African Republic of Liberia by the Yale University School of Forestry in Cooperation with the Firestone Plantations Company. Yale University, 1931.