Authors (if indicated). Organization responsible for the site. Title of page or document. Accessed Month day, year. Available at: URL.
Examples
Food and Drug Administration. MedWatch. Accessed June 13, 2007. Available at: http://www.fda.gov/medwatch/index.html.American Diabetes Association. Gestational diabetes. Accessed June 13, 2007. Available at: http://www.diabetes.org/gestational-diabetes.jsp.