Jihad Mohammed A. A STUDY FOR THE CAUSES OF VARIATION ORDERS IN DIFFERENT SECTORS OF CONSTRUCTION PROJECTS IN ERBIL GOVERNORATE FROM THE POINT OF VIEW OF THE INVOLVED PARTIES. J. eng. sustain. dev. [Internet]. 2016 Sep. 1 [cited 2025 Jul. 7];20(5):30-54. Available from: https://jeasd.uomustansiriyah.edu.iq/index.php/jeasd/article/view/718