http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Median family income and related data, by counties
[Department of Agriculture, Resource Development Economics Division, Economic Research Service]
by Claude C. Haren and Robert B. Glasgow
Bibliografía: p. 5-7 y notas bibliográficas a piede página.