Tolkien: The Illustrated Encyclopædia
by David Day.
Mitchell Beazley 1993 (1991)
This is a work that attempts to live up to its title: it includes an introduction to Tolkien’s published works (not just related to Middle Earth), then rushes straight into chapters on history, geography, peoples and nations (pretentiously called sociology here), natural history and a Who’s Who in Middle Earth, finally ending with indices and acknowledgements.
Because David Day doesn’t just limit himself to The Hobbit and The Lord of the Rings, there are charts and maps that help to place the War of the Ring in context, and the whole is profusely illustrated by nearly a score of artists.