Centre for Disease Control and Prevention. "Diphtheria Vaccination". Department of Health and Human Services. Arkiveret fra originalen 2. november 2011. Hentet 8. november 2011.
Centre for Disease Control and Prevention. "Diphtheria Vaccination". Department of Health and Human Services. Arkiveret fra originalen 2. november 2011. Hentet 8. november 2011.
"Diphtheria". who.int. 3. september 2014. Arkiveret fra originalen 2. april 2015. Hentet 27. marts 2015.