van der Gaag, N. (1999). National and regional population trends in the European Union: Nicole van der Gaag .. European Commission.
Chicagoスタイル(17版)引用形式van der Gaag, Nicole. National and Regional Population Trends in the European Union: Nicole Van Der Gaag .. Luxembourg: European Commission, 1999.
MLA(8版)引用形式van der Gaag, Nicole. National and Regional Population Trends in the European Union: Nicole Van Der Gaag .. European Commission, 1999.
警告: この引用は必ずしも正確ではありません.