This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.
Helman, C. (2016). The World’s Biggest Oil Companies, The World’s 25 Biggest Oil Companies: forbes.com (https://www.forbes.com/sites/christopherhelman/2012/07/16/the-worlds-25-biggest-oil-companies/#70ed1d9360ca).Search in Google Scholar