W. Intagun and  T. Khamdaeng and  P. Prom-ngarm and  N. Panyoyai,  Effect of Core Puncture Diameter on Bio-Char Kiln Efficiency.   journal   = {International Journal of Biotechnology and Bioengineering}, [online]. World Academy of Science, Engineering and Technology.
    October 2018, vol. 143(11). 435 - 439
    [viewed 17 November 2019]. Available from: https://publications.waset.org/pdf/10009773.