[1] http://www.globalchange.umich.edu/globalchange2/current/lectures/human_pop/human_pop.html

[2] http://www.equalearth.org/agriculturepollution.htm

[3] http://www.cnr.berkeley.edu/~agroeco3/modern_agriculture.html

[4] http://www.historyplace.com/worldhistory/famine/begins.htm

[5] http://www.sciencemag.org/cgi/content/abstract/314/5805/1598?rss=1

[6] http://www.fao.org/docrep/W4367E/w4367e0e.htm

[7] http://en.wikipedia.org/wiki/Arable_land

[8] http://www.msnbc.msn.com/id/16498079/site/newsweek/

[9] http://www.sciencedaily.com/releases/2007/01/070102140731.htm

[10] http://pmep.cce.cornell.edu/facts-slides-self/facts/mod-ag-grw85.html

[11] http://www.aces.uiuc.edu/news/stories/news3772.html

[12] http://dsc.discovery.com/news/2006/11/02/roboticweeder_tec.html?category=earth&guid=20061102134500

[13] http://www.calstate.edu/newsline/2007/n20070131fre1.shtml