1. Agricultural Marketing Service. 2009. United States standards for livestock and meat marketing claims, naturally raised claim for livestock and the meat and meat products derived from such livestock. Federal Register 74: 3541–3545.
2. Auriol, E., and S.G.M. Schilizzi. 2003. Quality signaling through certification: Theory and an application to agricultural seed markets. Working paper no 165, IDEI University of Toulouse, Toulouse, France.
3. Boström, M., and M. Klintman. 2003. Framing, debating, and standardising “natural food” in two different political contexts: Sweden and the U.S. Score working paper No. 2003:3, Stockholm Center for Organizational Research, Stockholm, Sweden.
4. California Institute for Rural Studies. 2005. Regulating organic: Impacts of the national organic standards on consumer awareness and organic consumption patterns. http://www.cirsinc.org/Documents/Pub1205.2.PDF . Accessed 17 July 2008.
5. Caswell, J.A., and E.M. Mojduszka. 1996. Using informational labeling to influence the market for food quality. American Journal of Agricultural Economics 78: 1248–1253.