1. Buhse L, Kolinski R, Westenberger B, Wokovich A, Spencer J, Chen CW, et al. Topical drug classification. Int J Pharm. 2005;295:101–12.
2. Osborne D. Review of changes in topical drug product classification. Pharm Tech. 2008;10:68–74.
3. FDA Approved Drug Products website (Drugs@FDA): http://www.accessdata.fda.gov/scripts/cder/drugsatfda/index.cfm
4. CDER Data Standard Manual- Dosage Form http://www.fda.gov/Drugs/DevelopmentApprovalProcess/FormsSubmissionRequirements/ElectronicSubmissions/DataStandardsManualmonographs/ucm071666.htm
5. Pharmaceutical Equivalence of Topical Dosage Forms, a presentation by R. Lionberger: http://www.fda.gov/ohrms/dockets/ac/05/…/2005-4137S2_04_Lionberger.ppt