Astuti Widi Rahayu, A. et al. 2020. ANALYSIS OF QUALITY IMPROVEMENT TO IMPROVE PRODUCTIVITY OF PISTON RING PVD WITH SIX SIGMA (DMAIC) APPROACH. International Journal of Psychosocial Rehabilitation. 24, 1 (Feb. 2020), 8128–8134. DOI:https://doi.org/10.61841/d0899b96.