Most Useful Reference / Encyclopedia Books

Vote on the reference or encyclopedia book you think is the most useful.
The Top Ten
1 Oxford Dictionary
2 The Chicago Manual of Style: The Essential Guide for Writers, Editors, and Publishers
3 Roget's Thesaurus
4 World Book Encyclopedia
5 Encyclopedia of Language and Linguistics
6 Columbia Encyclopedia
7 Encyclopedia Britannica

Useful for the 1700s

8 AP Stylebook
9 The Associated Press Stylebook 2019: And Briefing on Media Law
10 Collins Spanish Dictionary
The Contenders
11 The World Almanac and Book of Facts
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