Peters, Charles M.; Alwyn H. Gentry; Robert O. Mendelsohn (29 June 1989). «Valuation of an Amazonian rainforest». Nature339 (6227): 655–656. doi:10.1038/339655a0. Bibcode: 1989Natur.339..655P.
Belcher, B.M. (2003). «What isn't an NTFP?». International Forestry Review5 (2): 161–168. doi:10.1505/IFOR.5.2.161.17408.
Peters, Charles M.; Alwyn H. Gentry; Robert O. Mendelsohn (29 June 1989). «Valuation of an Amazonian rainforest». Nature339 (6227): 655–656. doi:10.1038/339655a0. Bibcode: 1989Natur.339..655P.