http://evolution.berkeley.edu/evolibrary/article/evo_25
http://www.bbc.co.uk/education/guides/z6trd2p/revision/3
http://healthresearchfunding.org/pros-cons-selective-breeding/
http://thenextgalaxy.com/selective-breeding-advantages-and-disadvantages-list/
http://www.actionbioscience.org/evolution/futuyma.html
http://www.globalchange.umich.edu/globalchange1/current/lectures/selection/selection.html