"Art in Ghana Postage Stamps" (Ph.D. diss., University of Science and Technology, Kumasi, Ghana, 1970).
"Portraiture in African Art" and "The Art of the Edo-Speaking Peoples outside Benin [with Phillip Peek]," The Art Dictionary, (London: Thames and Hudson, 1996).
"African Portraiture: A Commentary," ed. Jean Borgatti, Portraiture in Africa, Part II, African Arts 23, 4 (Oct 1990): 38-41.