Ananth, L., N. K. Gurbani, S. Kumar, and B. Gujavarti. “A Retrospective Study of Warning Letters Issued by US FDA over 2015-2017”. International Journal of Drug Regulatory Affairs, Vol. 6, no. 2, June 2018, pp. 48-53, doi:10.22270/ijdra.v6i2.242.