Winker, Margaret A., and Stephen J. Lurie. "Statistical Symbols and Abbreviations." AMA Manual of Style. 20090401. Oxford University Press. Date of access 19 Jun. 2013, <http://www.amamanualofstyle.com/view/10.1093/jama/9780195176339.001.0001/med-9780195176339-div1-216>.
Winker, M., & Lurie, S. (20090401). Statistical Symbols and Abbreviations. AMA Manual of Style. Retrieved 19 Jun. 2013, from http://www.amamanualofstyle.com/view/10.1093/jama/9780195176339.001.0001/med-9780195176339-div1-216.
Winker, Margaret A., and Stephen J. Lurie. "Statistical Symbols and Abbreviations." AMA Manual of Style. 19 Jun. 2013. http://www.amamanualofstyle.com/view/10.1093/jama/9780195176339.001.0001/med-9780195176339-div1-216.
Winker MA, Lurie SJ. Statistical symbols and abbreviations. In: AMA Manual of Style: A Guide for Authors and Editors. New York, NY: Oxford University Press; 2007. http://www.amamanualofstyle.com/view/10.1093/jama/9780195176339.001.0001/med-9780195176339-div1-216. Accessed June 19, 2013.