Siregar, Siddik, Eddy Irsan Siregar, and . . “Differentiation Strategy of Soes Construction Service in Indonesia: A Point of View of Project Managers”. International Journal of Engineering & Technology 7, no. 2.29 (May 22, 2018): 899–904. Accessed May 8, 2024. https://sciencepubco.com/index.php/ijet/article/view/14279.