1. Comstock G (2000) Are the policy implications of the precautionary principle coherent? Talk at Harvard University, 23 September 2000. http://www.cid.harvard.edu/cidbiotech/comments/comments72.htm
2. Cornell News (1999) Toxic pollen from widely planted, genetically modified corn can kill monarch butterflies, Cornell study shows. Cornell News. http://www.news.cornell.edu/releases/May99/Butterflies.bpf.html
3. EC (2001) Directive 2001/18/EC of the European Parliament and of the Council of 12 March 2001 on the deliberate release into the environment of genetically modified organisms and repealing Council Directive 90/220/EEC. In, Official Journal of the European Communities L106/1–38, 17.4.2001.
4. Graham G (2002) Genes: A Philosophical Inquiry. Routledge, London
5. Greenpeace (1999a) Monsanto and Novartis genetically engineered maize harms butterflies: Greenpeace calls for a ban. Greenpeace. http://archive.greenpeace.org/pressreleases/geneng/1999may20.html