D. I. De Souza and  D. Kipper and  G. P. Azevedo,  Comparing the Quality of Service of Bus Companies Operating in two Cities in Brazil.   journal   = {International Journal of Economics and Management Engineering}, [online]. World Academy of Science, Engineering and Technology.
    June 2012, vol. 66(6). 1033 - 1037
    [viewed 11 May 2024]. Available from: https://publications.waset.org/pdf/13927.