4Evans W E. Two- step heterocyclic nitrogen extraction from petroleum oil [p] US patent, 4960508, 1989.
5Olobunmi M. Ogunsola, Norbet Berkowitz. Removal of heterocyclie S and N from oil precursors by supercritieal water. Fuel,1995, 74(10) : 1485 - 1490.
6Shuguang Zhang, Qinglin Zhang. Extractive desulfurization and denitrogen of fuels using ionic liquids. Ind. Eng. Chem. Res 2004, 43:614 -622.
7Yasuhiro Shiraishi, Takayuki Hirai. Photochemical desulfurization and denitrogenation process for vacuum gas oil using an organic two phase extraction system. Ind.Eng. Chem. Res.
8Yasuhiro Shiraishi, Takayuki Hirai. Desulfurization and dinitrogenation process for light oils based chemical oxidation followed by liquid- liquid extraction. 2002,41: 4362 - 4375.
9Yasuhiro Shiraishi, Azumi Yamada. Desulfurization and denitrogenation of light oils by methyl viologen - modified aluminosilicate adsorbent. Energy&Fuel, 2004,18:1400 - 1404.