Craven, B. M., C. Fiala, A. Shiers, and G. T. Stewart. “Time Consistency and the Development of Vaccines to Treat HIV/AIDS in Africa”. Economic Issues, vol. 8, no. 1, Mar. 2003, pp. 15-31, http://economicissues.org.uk/index.php/EI_OJS/article/view/93.