"operon." A Dictionary of Nursing. Oxford University Press. 2008. Encyclopedia.com. 7 Nov. 2009 <http://www.encyclopedia.com>.
"operon." A Dictionary of Nursing. Oxford University Press. 2008. Encyclopedia.com. (November 7, 2009). http://www.encyclopedia.com/doc/1O62-operon.html
"operon." A Dictionary of Nursing. Oxford University Press. 2008. Retrieved November 07, 2009 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O62-operon.html