El Salvador; official standard names approved by the United States Board on Geographic Names.
APA Citation
United States. Office of Geography. (1956). El Salvador; official standard names approved by the United States Board on Geographic Names. Washington.
MLA Citation
United States. Office of Geography. El Salvador; Official Standard Names Approved by the United States Board On Geographic Names. Washington, 1956.
Warning: These citations may not always be complete (especially for serials).