Atlases are books with collections of maps, on a general area such as the World or a continent, on a country, or a topic.
Remember that an atlas will be broader in its coverage than an individual map. Topical atlases cover a very broad topic, such as climate, the environment, or population. Regional atlases will cover a large region or country. Keyword searches are very useful in a search for atlases, because there is no special subject term in the catalog for 'atlas'.
There will be both print books and e-books in your catalog searches.
A gazetteer is simply a list of geographic place names and their coordinates.
A name server is a searchable, online gazetteer.
The Columbia Gazetteer of the World (M.U. only)
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The Columbia Gazetteer of North America
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The Times Comprehensive Atlas of the World, 12th ed.
Merriam-Webster's Geographical Dictionary, 3rd ed.
Government Agency name servers, for U.S. and Canada federal governments.
Name Authorities are the boards responsible for the name server databases.