Nutt's The Legends of the Holy Grail.

Jusserand's Piers Plowman.

Warren's Langland's Vision of Piers the Plowman, Done into Modern
Prose
.

Savage's Old English Libraries.

Schofield's Chivalry in English Literature.

Snell's The Age of Chaucer.

Root's The Poetry of Chaucer.

Tuckwell's Chaucer (96 pp.).

Pollard's Chaucer (142 pp.).

Legouis's Chaucer.