Tchidi, Megan Florent, Zhen He, and Yan Bo Li. “Process and Quality Improvement Using Six Sigma in Construction Industry”. Journal of Civil Engineering and Management 18, no. 2 (April 2, 2012): 158-172. Accessed November 15, 2024. https://mma.vgtu.lt/index.php/JCEM/article/view/4435.