References

Centres for Disease Control and Prevention. (2017). Public Health Image Library (PHIL). Retrieved from: https://phil.cdc.gov/details.aspx?pid=130

Centers for Disease Control and Prevention. (2017). Polio Photos: Photo ID #5578. Retrieved from: https://www.cdc.gov/polio/us/photos.html

Public Health Ontario. (n.d.). Ontario’s Routine Immunization Schedule. Retrieved from: http://www.health.gov.on.ca/en/public/programs/immunization/static/immunization_tool.html