威廉·朗蘭 International PiersPlowman Society (页面存档备份,存于互联网档案馆) Website of international scholarly organization for the study of PiersPlowman and other alliterative
"Ex VI Transicionis" and its Passage in PiersPlowman. Blanch, Robert J. (编). Style and Symbolism in PiersPlowman: A Modern Critical Anthology. Knoxville