1. Borrow R, Balmer P, Roper MH. The immunological basis for immunization series. Module 3: Tetanus update 2006. Immunization, Vaccines and Biologicals. Geneva: World Health Organization, 2007. Available at: www.who.int/vaccines-documents/DocsPDF07/869.pdf
2. Scheifele DW, Ochnio JJ. The Immunological Basis for Immunization Series. Module 2: Diphtheria Update 2009. Immunization, Vaccines and Biologicals. Geneva: World Health Organization, 2009. Available at: whqlibdoc.who.int/publications/2009/9789241597869_eng.pdf
3. Rappuoli R. New and improved vaccines against diphtheria and tetanus. In: Levine MM, Woodrow GC, Kaper JB, Cobon GS, editors. New Generation Vaccines, 2nd Edition. New York: Marcel Dekker, 1997: 417-36
4. Coombes L, Stickings P, Tierney R, Rigsby P, Sesardic D. Development and use of a novel in vitro assay for testing of diphtheria toxoid in combination vaccines. J Immunol Methods 2009;350:142-9
5. World Health Organization. Requirements for diphtheria, tetanus, pertussis and combined vaccines. In: WHO Expert Committee on Biological Standardization. Fortieth Report. Geneva, World Heatlh Organization, 1990, Annex 2 (WHO Technical Report Series, No. 800). Available at: http://www.who.int/biologicals/publications/trs/areas/vaccines/dtp/en/index.html