Undercover operations (Espionage) -- See Espionage
--subdivision Secret service under names of wars, etc., e.g. World War, 1939-1945--Secret service; United States--History--Civil War, 1861-1865--Secret service
Underdeveloped areas -- See Developing countries Here are entered comprehensive works on those countries having relatively low per capita incomes.This heading may be subdivided by those topical subdivisions used under names of regions, countries, etc., e.g. Developing countries--Economic conditions, and may be used as a geographic subdivision under those topics authorized for local subdivision, e.g. Technology--Developing countries.
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Underdeveloped countries -- See Developing countries Here are entered comprehensive works on those countries having relatively low per capita incomes.This heading may be subdivided by those topical subdivisions used under names of regions, countries, etc., e.g. Developing countries--Economic conditions, and may be used as a geographic subdivision under those topics authorized for local subdivision, e.g. Technology--Developing countries.
