This is a short list of grail romances, pre-grail romances, and important studies on the grail. Happy reading!
Pre-Grail (i.e. Celtic or Apocryphal texts):
Grail texts (specifically using the word graal or grail)
Le Roman du Graal--The Romance of the Grail: French. Robert de Boron ca. 1195-1200.
Peredur: Welsh, found in the Mabinogion. ca. 1200-1250.
Perlesvaus, or The High History of the Holy Graal: French with British origins. ca. 1190-1210.
Didot Perceval, or Perceval le Gallois ou le conte du Graal: French, possibly the prose version of Robert de Boron's "Perceval". ca. 1210-1220
Parzival: German. Wolfram von Eschenbach ca. 1220.
The Vulgate Cycle, or Lancelot-Grail Cycle: French. Anonymous, attributed to Walter Map, but specifically by one or a small group of Cistercian monks. ca. 1220
Diu Krone--The Crown: German. Heinrich von dem Turlin. ca. 1220.
Sone de Nansi: French. ???
Le Morte d'Arthur: English. Sir Thomas Malory, 1475.
Useful Studies: