Rana Khalid Naeem and  Waseem Ahmed Khan and  Muhammad Akhtar and  Asif Mansoor,  Some Rotational Flows of an Incompressible Fluid of Variable Viscosity.   journal   = {International Journal of Physical and Mathematical Sciences}, [online]. World Academy of Science, Engineering and Technology.
    September 2009, vol. 33(9). 692 - 697
    [viewed 24 October 2021]. Available from: https://publications.waset.org/pdf/11824.