Ishak, I. S. ., S. . Mansor, T. . Mat Lazim, S. . Mat, M. Z. . Md. Zain, . R. E. . Mohd Nasir, and Z. . Mohd Ali. “Experimental Work on Unsteady Helicopter Rotor Hub Wakes”. Journal of Advanced Research in Fluid Mechanics and Thermal Sciences, vol. 65, no. 2, Dec. 2020, pp. 314-23, https://akademiabaru.com/submit/index.php/arfmts/article/view/2799.