Oladirin, Olugbenga Timothy, Samuel Olusola Olatunji, and Basir Tomiwa Hamza. 2013. “Effect of Selected Procurement Systems on Building Project Performance in Nigeria”. International Journal of Sustainable Construction Engineering and Technology 4 (1): 48-62. https://penerbit.uthm.edu.my/ojs/index.php/IJSCET/article/view/442.