Primary Source #31:

Goldfarb MT, Ellis CN, Weiss JS, Voorhees JJ. Topical tretinoin therapy: Its use in photoaged skin. Journal of the American Academy of Dermatology. 1989;21(3):645-650. doi:10.1016/S0190-9622(89)70232-2

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Feel free to use any of the images showcased on this website. Please cite both this website (UNC School of Medicine Dermatology Image Library - http://med.unc.edu/dil) and the primary source of the image as references.
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