Ha T. Pham and  Shuichi Miyagawa,  Historical Landscape Affects Present Tree Density in Paddy Field.   journal   = {International Journal of Environmental and Ecological Engineering}, [online]. World Academy of Science, Engineering and Technology.
    November 2014, vol. 95(11). 1217 - 1222
    [viewed 01 July 2022]. Available from: https://publications.waset.org/pdf/9999718.