1. https://www.ema.europa.eu/en/documents/referral/nitrosamines-emea-h-a53-1490-information-nitrosamines-marketing-authorisation-holders_en.pdf
2. A side reaction may have led to impurities found in valsartan heart drugs T. Nguyen in C&EN Chemical engineering news; Feb 19 2019.https://cen.acs.org/pharmaceuticals/process-chemistry/side-reaction-led-impurities-found/97/web/2019/02
3. EMA homepage.https://www.ema.europa.eu/en/human-regulatory/post-authorisation/referral-procedures/nitrosamine-impurities