United States Environmental Protection Agency: Protect Against Exposure on Formaldehyde. epa.gov/formaldehyde/protect-against-exposure-formaldehyde.
428
National Health Service: Carbon monoxide poisoning. nhs.uk/Conditions/Carbon-monoxide-poisoning/Pages/Introduction.aspx#causes.
429
Centers for Disease Control and Prevention. National Center for Environmental Health: Carbon Monoxide Poisoning. Frequently Asked Questions. cdc.gov/co/faqs.htm.
