1. Chaparro L, Terradas J (2009) Ecological Services of Urban Forest in Barcelona. Centre de Recerca Ecològica I Aplicacions Forestals, Universitat Autònoma de Barcelona, Bellaterra, Spain. 96 p. http://www.itreetools.org/resources/reports/Barcelona%20Ecosystem%20Analysis.pdf Accessed: 22 February 2012.
2. Ciesla WM (2001) Tomicus piniperda. North American Forest Commission. Exotic Forest Pest Information System for North America (EXFOR). http://spfnic.fs.fed.us/exfor/data/pestreports.cfm?pestidval=86&langdisplay=english Accessed 19 March 2012
3. City of Toronto (2011) Every tree counts: a portrait of Toronto’s Urban Forest. City of Toronto parks, Forestry and Recreation, Urban Forestry. 63 p. http://www.toronto.ca/trees/pdfs/Every_Tree_Counts.pdf Accessed 22 February 2012
4. Clarke SR, Nowak JT (2009) Southern Pine Beetle. USDA Forest Service, Forest Insect & Disease Leaflet 49. http://www.fs.fed.us/r6/nr/fid/fidls/fidl-49.pdf Accessed 19 March 2012
5. Council of Tree and Landscape Appraisers (1992) Guide for plant appraisal. International Society of Arboriculture, Savoy