Lawrence Kohlberg, "Stage and Sequence: The Cognitive Developmental Approach to Socialization," in D.A. Goslin, ed., /Handbook of Socialization Theory and Research/ (Rand-McNally Co, Chicago, 1969), pp. 347-380.
See also John C. Gibbs, "Kohlberg's Stages of Moral Development: A Constructive Critique," /Harvard Educational Review/ 47(1): 43-61 (1977).