1. Ridley DS. Pathogenesis of leprosy and related diseases. London: Wright; 1988.
2. Ridley DS, Jopling WH. A classification of leprosy for research purposes. Lepr Rev. 1962;33:119–28.
3. Ridley DS, Jopling WH. Classification of leprosy according to immunity—a five-group system. Int J Lepr Other Mycobact Dis. 1966;34:255–73.
4. Ridley DS. Nature of the leprosy spectrum. In: Ridley DS, editor. Pathogenesis of leprosy and related diseases. London: Wright; 1988. p. 93–105.
5. Noto S, Clapasson A, Nunzi E. Classification of leprosy: the mystery of “reactional tuberculoid”. G Ital Dermatol Venereal. 2007;142:294–5.