http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Application of international standards to census data on the economically active population
United Nations publications. Sales number: 1951. XIII. 2.
United Nations. [Document] ST/SOA/Series A/9
Population studies (New York, N.Y.) ; no. 9