Oppmann, Lesley, Blom et al.: "Novel p19 protein engages IL-12p40 to form a cytokine, IL-23, with biological activities similar as well as distinct from IL-12." in: Immunity, Vol. 13, Issue 5, pp. 715-25, 2001 (PubMed).
Hunter: "New IL-12-family members: IL-23 and IL-27, cytokines with divergent functions." in: Nature reviews. Immunology, Vol. 5, Issue 7, pp. 521-31, 2005 (PubMed).