1. Energy Information Administration (EIA), 2004, Chemical Industry Briefs: Energy Consumption, retrieved from http://www.eia.doe.gov/emeu/mecs/iab98/chemicals/energy_use.html.
2. Manufacturing Energy Consumption Survey (MECS), Table N3.2 Fuel Consumption, retrieved from http://www.eia.doe.gov/emeu/mecs/mecs98/datatables/d98n3_2.htm.
3. Energy Information Administration (EIA), EIA Database, Energy Consumption: Energy Consumption by Fuel, retrieved from http://www.eia.doe.gov/emeu/mecs/iab98/chemicals/fuel.html.
4. Energy Information Administration (EIA), EIA Natural Gas Navigator, retrieved from http://tonto.eia.doe.gov/dnav/ng/ng_cons_acct_dcu_nus_a.htm.
5. The North American Industrial Classification Systems (NAICS), retrieved from the U.S. Census Bureau Website at http://www.census.gov/epcd/www/naics.html.