Columbia subject headings:
Grail--Legends--History and criticism.
Harvard subject headings:
Arthurian romances--History and criticism.
Grail--Legends--History and criticism
Knights and knighthood in literature.
Literature, Medieval--History and criticism
Quests (Expeditions) in literature.
Romances--History and criticism.
Princeton subject headings:
Grail--Legends--History and criticism.