Winker, Margaret A., and Stephen J. Lurie. "Significant Digits and Rounding Numbers." AMA Manual of Style. 20090401. Oxford University Press. Date of access 18 Jun. 2013, <http://www.amamanualofstyle.com/view/10.1093/jama/9780195176339.001.0001/med-9780195176339-div1-214>.
Winker, M., & Lurie, S. (20090401). Significant Digits and Rounding Numbers. AMA Manual of Style. Retrieved 18 Jun. 2013, from http://www.amamanualofstyle.com/view/10.1093/jama/9780195176339.001.0001/med-9780195176339-div1-214.
Winker, Margaret A., and Stephen J. Lurie. "Significant Digits and Rounding Numbers." AMA Manual of Style. 18 Jun. 2013. http://www.amamanualofstyle.com/view/10.1093/jama/9780195176339.001.0001/med-9780195176339-div1-214.
Winker MA, Lurie SJ. Significant digits and rounding numbers. 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-div1-214. Accessed June 18, 2013.