1. Schmidt V. Defining heavy oil. World oil. FindArticles.com, ; 2010.
2. Delayed coking schemes are most economical for heavy-oil upgrading;Vartivarian;Oil Gas J,2006
3. Atkins L, Higgins T, Barnes C. Heavy crude oil: global analysis and outlook to 2030. Hart energy consulting report; November 2010.
4. . US energy information administration-independent statistics and analysis. Country analysis briefs [Retrieved 2010-10-05].
5. Solari RB, Marzin R, Zbinden H. Comparison of carbon rejection and hydrogen addition processes in production-upgrading complexes. 15th World Petroleum Congress, Beijing, China; October 12–17, 1997.