N. Abdalla, Ahmed, Kharudin Ali, Johnny Koh Siaw Paw, Chong Kok Hen, Tan Jian Ding, M Sham Maizal, and M Izzat. 2018. “Crack Identification Using Piezoelectric Testing on Carbon Steel Pipe for Transverse, Longitudinal and Hole Defects With Low Excitation Frequency”. International Journal of Engineering & Technology 7 (2.14): 171-76. https://doi.org/10.14419/ijet.v7i2.14.12819.