1. Agra CEAS, 2004. Study on the socio-economic implications of the various systems to keep laying hens. Final Report for the European Commission, December.
2. The market for ‘Lemons’, quality uncertainty and the market mechanism;Akerlof;Quarterly Journal of Economics,1970
3. Bagwell, K., and Staiger, R.W., 1999. Domestic policies, national sovereignty and international economic institutions. NBER Working Paper 7293. Cambridge.
4. The Theory of Environmental Policy;Baumol,1988
5. Beers, C., van and van den Bergh, J.C.J.M., 2000. The impact of environmental policy on foreign trade. Tinbergen Institute Discussion Paper TI 2000-069/3. Amsterdam.