Aini Sulaiman, Noorul, et al. “Optimization of Alkaline Protease Production by Alkaliphilic Bacillus Lehensis G1 Using Statistical Design”. International Journal of Engineering and Technology, vol. 7, no. 4.38, Dec. 2018, pp. 1651-4, https://doi.org/10.14419/ijet.v7i4.38.29225.