Performance Improvement of the Implementation of Concrete Structures in the Construction Sector In Iraq Using The Modern Management Technique “Six Sigma”. Journal of Engineering, [S. l.], v. 21, n. 01, p. 13–29, 2015. DOI: 10.31026/j.eng.2015.01.10. Disponível em: https://joe.uobaghdad.edu.iq/index.php/main/article/view/482.. Acesso em: 6 may. 2024.