Fontanarosa, Phil B., and Stacy Christiansen. "Visual Acuity." AMA Manual of Style. 20090401. Oxford University Press. Date of access 20 May. 2013, <http://www.amamanualofstyle.com/view/10.1093/jama/9780195176339.001.0001/med-9780195176339-div2-492>.
Fontanarosa, P., & Christiansen, S. (20090401). Visual Acuity. AMA Manual of Style. Retrieved 20 May. 2013, from http://www.amamanualofstyle.com/view/10.1093/jama/9780195176339.001.0001/med-9780195176339-div2-492.
Fontanarosa, Phil B., and Stacy Christiansen. "Visual Acuity." AMA Manual of Style. 20 May. 2013. http://www.amamanualofstyle.com/view/10.1093/jama/9780195176339.001.0001/med-9780195176339-div2-492.
Fontanarosa PB, Christiansen S. Visual acuity. In: AMA Manual of Style Committee. AMA Manual of Style: A Guide for Authors and Editors. 10th edition ed. New York, NY: Oxford University Press; 2007:796. http://www.amamanualofstyle.com/view/10.1093/jama/9780195176339.001.0001/med-9780195176339-div2-492. Accessed May 20, 2013.