Sources:
1. National Foundation for Infectious Diseases. Facts about tetanus for adults. Available at: http://www.nfid.org/pdf/factsheets/tetanusadult.pdf. Accessed August 7, 2009.
2. National Foundation for Infectious Diseases. Facts about diphtheria for adults. Available at: http://www.nfid.org/pdf/factsheets/diphtadult.pdf. Accessed August 7, 2009.