Olayiwola, Y. B., O. A. Oluyege, and L. Labunmi. “Direct Solvent Liquefaction of Tropical Hardwood Bark and Characterization of the Resulting Bio-Oil”. Journal of Energy Research and Reviews, Vol. 5, no. 1, May 2020, pp. 1-7, doi:10.9734/jenrr/2020/v5i130137.