http://epw.senate.gov/public/index.cfm?FuseAction=Minority.B... http://www.sciencedaily.com/releases/2003/03/030321075236.ht... http://www.aip.org/pnu/2003/split/642-2.html
Studies: http://www.standaard.be/Artikel/Detail.aspx?artikelid=B18307... http://www.sciencedaily.com/releases/2007/08/070801174450.ht... http://www.sciencedaily.com/releases/2007/08/070801175711.ht...
http://epw.senate.gov/public/index.cfm?FuseAction=Minority.B... http://www.sciencedaily.com/releases/2003/03/030321075236.ht... http://www.aip.org/pnu/2003/split/642-2.html
Studies: http://www.standaard.be/Artikel/Detail.aspx?artikelid=B18307... http://www.sciencedaily.com/releases/2007/08/070801174450.ht... http://www.sciencedaily.com/releases/2007/08/070801175711.ht...