1. British Petroleum (BP), http://www.bp.com/liveassets/bp_internet/globalbp/globalbp_uk_english/reports_and_publications/statistical_energy_review_2008/STAGING/local_assets/downloads/pdf/oil_table_of_world_oil_production_million_tonnes_2008.pdf (last visited: 2 June 2009).
2. British Petroleum (BP), http://www.bp.com/liveassets/bp_internet/globalbp/globalbp_uk_english/reports_and_publications/statistical_energy_review_2008/STAGING/local_assets/downloads/pdf/gas_table_of_natural_gas_production_million_tonnes_2008.pdf (last visited: 2 June 2009).
3. Degrange, J.-P., and S. Lepicard (2004), Evaluation of occupational radiological exposures associated with fly ash from French coal power plants, Proc. Int. Conference ‘Naturally Occurring Radioactive Materials’ (NORM IV), 17–21 May 2004, Szczyrk, Poland, IAEA-TECDOC-1472, Vienna, 230–239.
4. IAEA (1996), International basic safety standards for protection against ionizing radiation and for the safety of radiation sources, International Atomic Energy Agency, IAEA Safety Standards, Safety Series 115.
5. IAEA (2003), Extent of environmental contamination by Naturally Occurring Radioactive Material (NORM) and technological options for mitigation, International Atomic Energy Agency, IAEA Technical Report Series 49.