C. R., J., D. R. N., and S. B. L. “Efficacy and Safety of Topical BAK-Free Travoprost 0.004% Versus BAK-Preserved Travoprost 0.004% in the Treatment of Primary Open Angle Glaucoma: A Comparative Study at a Tertiary Care Hospital”. International Journal of Basic & Clinical Pharmacology, vol. 6, no. 9, Aug. 2017, pp. 2199-05, doi:10.18203/2319-2003.ijbcp20173744.