WASET
    Akihiro Iijima and  Kimiyo Kumagai,  Changes in Fine PM Pollution Levels with Tightening of Regulations on Vehicle Emissions.   journal   = {International Journal of Environmental and Ecological Engineering}, [online]. World Academy of Science, Engineering and Technology.
    December 2012, vol. 72(12). 788 - 791
    [viewed 19 September 2024]. Available from: https://publications.waset.org/pdf/6567.