Columbia subject headings:
Chrétien, de Troyes, active 12th century. Perceval le Gallois.
Grail.
Harvard subject headings:
Chrétien, de Troyes, active 12th century. Perceval le Gallois
Grail.
Princeton subject headings:
Chrétien, de Troyes, active 12th century. Perceval le Gollois.
Grail.