1. Lindblad, A. R., Preparation of oils from wood by hydrogénation. Ing. Vetenskap Akad. Handl., 107 (1931) 7–59.
2. Ipatiew, W. & Petrow, D., Über die pyrogene Zersetzung von Holzteer in Gegenwart von Wasserstoff und unter Druck. Angew. Chem., 1 (1928) 172–6.
3. Berl, E., The production of oil from plant materials. Science, 99 (1944) 309–12.
4. Oshima, M., Maeda, Y. & Kashima, K., Process for liquefaction of lignin. Canadian Patent 700 209, 1964.
5. Goheen, D. W., Low molecular weight chemicals. In Lignin— Occurrence, Formation, Structure, and Reactions, ed. A. V. Sarkanen & C. H. Ludwig. Wiley-Interscience, New York, 1971, pp. 797–832.