There is an original and 2 reincarnations of the Garland Arthurian Encyclopedia:
1) The Garland original hardback
(1986), with a black cover with gold lettering, is out of print. The
paperback version of it published by Peter Bedrick Books, in either a red or
a yellow cover, depending on the year of reprinting. It covers both medieval
and most modern subjects reasonably well with about 700 entries. The main
disadvantage is that it has no index; instead, there are cross-references
within the text.
2) The New Arthurian Encyclopedia
(Garland, 1991) exists in hardback. An updated edition was published in 1995
in hardback and paperback of this precise version and it expands or recasts
about 100 of the original entries and adds about 500 new entries. Some
of the new ones are on medieval material missing from 1st edition, but most
are on novels, poems, films, and items that had appeared since about 1985.
In addition, there is a full index, which makes it more easily used. The
format has been changed from full-page text to double columns; the
illustrations, almost double the number from the first edition, have been
carefully chosen and placed to augment entries and please the eye. The
excellent selected bibliography has been expanded and updated to 1990
publications. Most significant are the additional entries about 20th-century
Arthurian writers and poets.
3) The New Arthurian Encyclopedia, Updated Edition (1996) is mainly a paperback reprint of the 2nd version, but in addition, there is a supplement with a couple of hundred new entries. The new material is alphabetized in the back of the book but not integrated into the main text and not included in the index. A chronology of landmarks in Arthurian history, archealogy, literature and art. A map showing major sites in Arthurian legend and history. More than 1,300 entries made by over 130 contributors. 92 photographs and illustrations. More than 90 entries on Arthurian characters.