Tertiary sources compile, summarize, index, or help identify scholarly sources on a topic. They are useful for background research or to get an overview of a topic before delving into secondary or primary sources. Common tertiary sources for literature, media and communication include dictionaries, encyclopedias, handbooks, and other reference sources.
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The OED online can be used to perform simple searches for word definitions, or for full-text searching of all OED's definitions, etymologies and quotations through the Search function.
