Vision of William concerning ... 1900.

Vasilev, G. Bŭlgarski bogomilski i apokrifni ... 2001: t.p. (Uĭli︠a︡m Langland)

Wikipedia, Feb. 13, 2013 (William Langland (ca. 1332-ca. 1386) is the conjectured author of the 14th-century English dream-vision Piers Plowman)

Britannica online, Feb. 13, 2013 (William Langland, (born c. 1330-died c. 1400), presumed author of one of the greatest examples of Middle English alliterative poetry, generally known as Piers Plowman)

Piers Plowman electronic archive, viewed on Feb. 13, 2013: About > About William Langland (William Langland (ca. 1325 - ca. 1390); it is not certain when William Langland was born, but based on contemporary references in the earliest version of Piers Plowman (=A Text), it seems the earliest plausible date for his birth is ca. 1325 and the latest plausible date is ca. 1330; scholars assumed that Langland must have died before 1387; however, some scholars recently have pushed Langland's death-date to at least 1390) http://piers.iath.virginia.edu/about/williamLangland.html

Luminarium website, Feb. 13, 2013 (William Langland (c. 1330-1387))