Of potential interest:
Jimenez, Phil, et al. The DC Comics Encyclopedia: The Definitive Guide to the Characters of the DC Universe. New York: DK Publishing, 2004. ISBN 0-7566-0592-X.
This is basically an updating of the earlier Who's Who from the 1980s. Arthurian references occur in entries on The Demon (and his related cast), Morgaine Le Fey, and Tor, Magic Master (for Quality's Merlin the Magician).
Also of note--did list members know that one of the Three Witches--the crone--is named Mordred (see p. 309). The others are Mildred (the mother) and Cynthia (the maiden).
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