1. Langer, W.L. Sci. Am. 234, 112–117 (1976).
2. Abbas, A.K., Lichtman, A.H. & Pillai, S. Cellular and Molecular Immunology 6th edn. (Saunders Elsevier, Philadelphia, 2007).
3. Ba, D. Chin. J. Immunol. 20, 7–9 (2004).
4. Cao, X. et al. J. Immunol. 161, 6238–6244 (1998).
5. Yao, X. et al. Vaccine 25, 1771–1779 (2007).