1. http://www.manufacturingchemist.com/technical/article_page/In_the_business_of_winning/62168.
2. http://www.iptonline.com/articles/public/NanoGuardian.pdf.
3. http://www.drugs.com/news/fda-guideline-calls-more-secure-pharmaceutical-supply-chain-covectra-offers-robust-solutions-27974.html.