Wei Hua Ho,  Location of Vortex Formation Threshold at Suction Inlets near Ground Planes – Ascending and Descending Conditions.   journal   = {International Journal of Aerospace and Mechanical Engineering}, [online]. World Academy of Science, Engineering and Technology.
    November 2011, vol. 59(11). 2370 - 2377
    [viewed 19 October 2019]. Available from: https://publications.waset.org/pdf/15812.