1. Regulatory Impact Analysis of the United States Environmental Protection Agency EPA420-r00-026.
2. Brussels COM (11.05.2001) 241 Final (BS EN 590-2004/DIN EN 590-2004), Automotive Fuels, Diesel, Requirements and Test Methods; and 2003/17/EC OJ L 76;Directive of the European Parliament and of the Council,22232003
3. US crude slate gets heavier, higher in sulfur;Swain;Oil Gas J.,1991
4. Extractive de-sulfurization and de-ashing of high sulfur coals by oxidation with ionic liquids