For a general introduction to the place of Piers
Plowman in literary tradition you may usefully consult the
following online resources:
The Luminarium website on William Langland.
The Wikipedia entries for Piers Plowman and William Langland are
for the most part quite trustworthy.
John Matthews Manly's chapter on '"Piers Plowman" and its Sequence'
in The End
of the Middle Ages, vol. 2 in the Cambridge History
of English Literature (1907-27), though a century old and out
of line with modern views regarding authorship, still contains lots of
useful information about the poems, their contexts, and their legacy.
The Introduction
to Knott and Fowler's edition of the A Version may also prove
useful.
(7 January 2008)