Roewer, U. (2008). Environmental Protection Expenditure by Industry in the European Union 1997-2004. Statistic in focus: Environment and energy.
Chicago-Zitierstil (17. Ausg.)Roewer, Ute. "Environmental Protection Expenditure by Industry in the European Union 1997-2004." Statistic in Focus: Environment and Energy 2008.
MLA-Zitierstil (8. Ausg.)Roewer, Ute. "Environmental Protection Expenditure by Industry in the European Union 1997-2004." Statistic in Focus: Environment and Energy, 2008.
警告：這些引文格式不一定是100％准確.