Chhabra, H., A. Gupta, and G. Singh. “A Comparative Study of Benzalkonium Chloride-Free Latanoprost Versus Benzalkonium Chloride-Preserved Latanoprost on Ocular Surface Health in Patients of Primary Open Angle Glaucoma”. International Journal of Basic & Clinical Pharmacology, vol. 6, no. 5, Apr. 2017, pp. 1110-4, doi:10.18203/2319-2003.ijbcp20171660.