1. Workers Compensation Board of BC 2000 5
2. Washington State Department of Labor and Industries http://www.lni.wa.gov/Safety/Topics/AtoZ/HazardsVeterinary/default.asp
3. Canadian Centre for Health and Safety http://www.ccohs.ca/oshanswers/diseases/rmirsi.html#tphp
4. Ionizing Radiation, Toxic and Hazardous Substances Part Number 1910, Subpart Z;OSHA;Standard number,1974
5. U.S Department of Labor, Occupational Health and Safety Division http://www.osha.gov/dts/osta/anestheticgases/index.html