W.C. Woon, W.K. Hoi, and Puad Elham. 1989. “ECONOMICS OF RUBBERWOOD CHARCOAL PRODUCTION USING THE TRANSPORTABLE METAL KILN”. Journal of Tropical Forest Science (JTFS) 1 (4):327-35. https://jtfs.frim.gov.my/jtfs/article/view/2179.