Gebriel M. Shamia,  Statistical Properties and Performance of Ecological Indices Based On Relative Abundances.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    March 2013, vol. 75(3). 396 - 401
    [viewed 17 October 2019]. Available from: https://publications.waset.org/pdf/287.