Barton: Select "Subject begins with" and enter child labor.

U.S. Bureau of Labor Statistics: Enter child labor in the search box.

World Bank Labor and Social Protection: Enter child labor in the search box. You will also need to enter the name of a country to see the data on a chart.

World Development Indicators: See topics under "child employment" in Series list. You will also need to select a country and time period to display the data.

International Labour Organization Child Labour page.