„3 Concept and classification“. Global ecological zoning for the global forest resources assessment 2000. Rome: UN Food and Agriculture Organization. Forestry Department. 2001. Suarchyvuota iš originalo July 21, 2010. Nuoroda tikrinta December 30, 2011.
„3 Concept and classification“. Global ecological zoning for the global forest resources assessment 2000. Rome: UN Food and Agriculture Organization. Forestry Department. 2001. Suarchyvuota iš originalo July 21, 2010. Nuoroda tikrinta December 30, 2011.