Bagus Prasetiyo, A., K. A. . Sekarjati, and A. E. Tontowi. “Application of RSM Method in Optimization of 3D Printing Machine Process Parameters Using Biocomposite Materials (PMMA/Hydroxyapatite) to Get the Highest Tension Strength”. Journal of Energy, Mechanical, Material, and Manufacturing Engineering, vol. 6, no. 2, Dec. 2021, pp. 119-26, doi:10.22219/jemmme.v6i2.17780.