Abdul Rahim, Mustaqqim, Shahiron Shahidan, Choon Onn Lee, Nur Amira Afiza Saiful Bahari, Norashidah Abd Rahman, and Afizah Ayob. 2020. “The Behavior of Non-Destructive Test for Different Grade of Concrete”. International Journal of Integrated Engineering 12 (9), 1-8. https://publisher.uthm.edu.my/ojs/index.php/ijie/article/view/5336.