Columbia subject headings:
Child labor--Cross-cultural studies.
Child prostitution--Cross-cultural studies.
Slavery--History--20th century.
Harvard subject headings:
Child labor--Cross-cultural studies.
Child prostitution--Cross-cultural studies.
Slavery--History--20th century.
Princeton subject headings:
Child labor--Cross-cultural studies.
Child prostitution--Cross-cultural studies.
Slavery--History--20th century.