Bills, D. B. (2003). Credentials, signals, and screens: Explaining the relationship between schooling and job assignment. Review of Educational Review, 73(4), 441-449. Retrieved from http://rer.sagepub.com/content/73/4/441.abstract#cited-by
Bills (2003) presented and examined a set of theories that explain the relationship between credentials and socioeconomic attainment, including human capital, screening and filtering, signaling, cultural capital, and credentialist theories.