Shinji Kawakura and  Ryosuke Shibasaki,  Various Advanced Statistical Analyses of Index Values Extracted from Outdoor Agricultural Workers Motion Data.   journal   = {International Journal of Nutrition and Food Engineering}, [online]. World Academy of Science, Engineering and Technology.
    March 2014, vol. 91(7). 790 - 797
    [viewed 21 February 2020]. Available from: https://publications.waset.org/pdf/10001086.