1. Versieck A, Cornelis R (1989) Trace elements in human plasma and serum. CRC Press, Boca Raton
2. Draelos ZD (2001) Special considerations in eye cosmetics. Clin Dermatol 19:424–430
3. U.S. FDA. Part 73 (2018)
https://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&SID=fc2869830da702969a2dcfdeb71d7594&rgn=div5&view=text&node=21:1.0.1.1.27&idno=21#21:1.0.1.1.27.3
. Accessed 11 May 2018
4. Council Directive 76/768/EEC (1976)
https://eur-ex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:1976L0768:20100301:en:PDF
. Accessed 15 May 2018
5. ANVISA—Brazilian Health Regulatory Agency (2012)
http://portal.anvisa.gov.br/documents/10181/3285555/RDC_44_2012_.pdf/a2489836-8233-40bc-b880-c7719ae356fc
. Accessed 15 May 2018