Atkinson, W; Hamborsky, J; McIntyre, L; Wolfe, S, eds. (2005). "Smallpox"(PDF). Epidemiology and Prevention of Vaccine-Preventable Diseases (The Pink Book) (9th ed.). Washington DC: Public Health Foundation. pp. 281–306. Archived from the original(PDF) on 2010-04-09. {{cite book}}: |website= ignored (help)
ec.gc.ca
Environment Canada. "Lower Mainland Ecoregion" Narrative Descriptions of Terrestrial Ecozones and Ecoregions of Canada (No. 196). Retrieved on: August 3, 2007. Archived January 27, 2007, at the Wayback Machine
Atkinson, W; Hamborsky, J; McIntyre, L; Wolfe, S, eds. (2005). "Smallpox"(PDF). Epidemiology and Prevention of Vaccine-Preventable Diseases (The Pink Book) (9th ed.). Washington DC: Public Health Foundation. pp. 281–306. Archived from the original(PDF) on 2010-04-09. {{cite book}}: |website= ignored (help)
Environment Canada. "Lower Mainland Ecoregion" Narrative Descriptions of Terrestrial Ecozones and Ecoregions of Canada (No. 196). Retrieved on: August 3, 2007. Archived January 27, 2007, at the Wayback Machine