Chart 30.1 Impact factor for energy journals in natural sciences, 2010. In a given year, the impact factor of a journal is the average number of citations received per paper published in that journal during the two preceding years. Source: Data from Thomson Reuters, Journal Citation Reports^®, <http://thomsonreuters.com/products_services/science/science_products/a-z/journal_citation_reports/>.

Chart 30.2 Impact factor for energy journals in social sciences, 2010. In a given year, the impact factor of a journal is the average number of citations received per paper published in that journal during the two preceding years. Source: Data from Thomson Reuters, Journal Citation Reports^®, <http://thomsonreuters.com/products_services/science/science_products/a-z/journal_citation_reports/>.