Azhar, Afif Aiman, and Ahmad Fahmy Kamarudin. 2021. “Effect of Vertical Irregularity(Lower Level) of 5-Storey Laboratory Steel Tower Using Modal Parameters”. Recent Trends in Civil Engineering and Built Environment 2 (1): 362-71. https://penerbit.uthm.edu.my/periodicals/index.php/rtcebe/article/view/1464.