FDA 2009: United States Food and Drug Administration. 2009. Specific Labeling Requirements for Specific Drug Products. Code of Federal Regulations Title 21, Volume 4 (21CFR201.319). Rockville (MD): United States Department of Health and Human Services, U.S. Food and Drug Administration. [Accessed 2009-12-23]. Available from: http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=201.319