Erawati, W., and P. Ramdani. “Rancang Bangun Sistem Informasi Pembelian Bahan Baku Pada PT. Herba Medica Lestari Dengan Metode Waterfall”. Journal of Information System Research (JOSH), Vol. 1, no. 1, Oct. 2019, pp. 37-44, https://ejurnal.seminar-id.com/index.php/josh/article/view/38.