1. Guidelines for Application of the Petroleum Resources Management System, http://www.spe.org/industry/docs/PRMS_Guidelines_Nov2011.pdf; November 2011.
2. OGJ Worldwide Production Reports, http://www.ogj.com/articles/print/volume-111/issue-12/special-report-worldwide-report/worldwide-reserves-oil-production-post-modest-rise.html.