WASET
    Reyna Singh and  David Lokhat and  Milan Carsky ,  A Two-Step, Temperature-Staged Direct Coal Liquefaction Process .   journal   = {International Journal of Chemical and Molecular Engineering}, [online]. World Academy of Science, Engineering and Technology.
    September 2015, vol. 103(7). 896 - 902
    [viewed 25 April 2024]. Available from: https://publications.waset.org/pdf/10002510.