Langland, William: A brief biography at infoplease.com.
Meed, Mercede, and Mercy - Langland's Grammatical Metaphor and Its Relation to Piers Plowman as a Whole: Essay from Medieval Perspectives. Includes notes and works cited.
Piers Plowman and the Sublime: Essay by Murray J. Evans.
William Langland (ca.1330-1387): Includes a short biography, essays, and a link to the e-text of Piers Plowman.
Yearbook of Langland Studies: Features an annual bibliography, the current issue, and sample pages.