1. Köhler, H. Christmas address,
http://www.bundespraesident.de/rede-,2.642777/Ein-neues-Miteinander-von-Jung.htm
(2007).
2. Kovas, Y., Haworth, C. M., Dale, P. S. & Plomin, R. Monogr. Soc. Res. Child Dev. 72, 1–44 (2007).
3. Anderson, D. & Brenner, S. Nature 451, 139 (2008).
4. http://www.time.com/time/magazine/article/0,9171,915567,00.html
5. http://www.dwp.gov.uk/pensionsreform/pdfs/GenderImpactAssessment-5-Dec2007.pdf