D. A. Firdaus, F. H. Jihad, and S. I. M. Mursaha, “Sources of cysteine-based pharmaceutical drugs and their halal aspects in product development”, Halal Stud. Soc., vol. 1, no. 1, pp. 34–37, Dec. 2023, doi: 10.29244/hass.1.1.34-37.