baitha P. maggadani, harmita, yahdiana harahap, and H. L. N. HUTABALIAN, “SIMULTANEOUS IDENTIFICATION AND QUANTIFICATION OF HYDROQUINONE, TRETINOIN AND BETAMETHASONE IN COSMETIC PRODUCTS BY ISOCRATIC REVERSED PHASE HIGH PERFORMANCE LIQUID CHROMATOGRAPHY”, Int J App Pharm, vol. 11, no. 3, pp. 181–185, May 2019.