3[3]Hunter M G, Pappal D A, Pesek C L. NPRA, AM-94-21
4[4]Sztenderowicz M. Base Oils to Meet Future Lubricant Requirements; ILSAC GF-3 and Beyond NPRA AM-97-53
5[5]Chang Jie, Liu Jiansheng. Li Dadong. Kinetics of Residue Hydrotreating Reactions, International Symposium on the Advances in Catalysis and Process for Heavy Oil Conversion, 1997