1. Exogenous ochronosis
2. Hydroquinone Task Group, Nonprescription Drug Manufacturers Association. Salient observations from the published literature on exogenous ochronosis reportedly associated with skin discoloration fade products. Washington, DC: Nonprescription Drug Manufacturers Association; 12 May 1992.
3. Skin lightening preparations and the hydroquinone controversy
4. The safety of hydroquinone
5. The safety of hydroquinone: A dermatologist's response to the 2006 Federal Register