Παραπομπή APA
Library of Congress. (1980). Library of Congress subject headings (9th ed.). Washington: Library of Congress.
Παραπομπή Chicago StyleLibrary of Congress. Library of Congress Subject Headings. 9th ed. Washington: Library of Congress, 1980.
Παραπομπή MLALibrary of Congress. Library of Congress Subject Headings. 9th ed. Washington: Library of Congress, 1980.
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