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Emery 1996, p. 240; Pettifer 2002, p. 272; "History and Research: Piel Castle", English Heritage, retrieved 12 October 2013 Emery, Anthony (1996). Greater Medieval Houses of England and Wales, 1300-1500. Vol. 1. Cambridge, UK: Cambridge University Press. ISBN9780521497237. Pettifer, Adrian (2002). English Castles: A Guide by Counties. Woodbridge, UK: Boydell Press. ISBN978-0-85115-782-5.
Emery 1996, p. 240; "History and Research: Piel Castle", English Heritage, retrieved 12 October 2013 Emery, Anthony (1996). Greater Medieval Houses of England and Wales, 1300-1500. Vol. 1. Cambridge, UK: Cambridge University Press. ISBN9780521497237.
Emery 1996, p. 241; "History and Research: Piel Castle", English Heritage, retrieved 12 October 2013 Emery, Anthony (1996). Greater Medieval Houses of England and Wales, 1300-1500. Vol. 1. Cambridge, UK: Cambridge University Press. ISBN9780521497237.
Wood 1992-93, p. 18; Mackenzie 1896, p. 186; Pettifer 2002, p. 272; "List Entry Summary: Piel Castle", English Heritage, archived from the original on 24 October 2014, retrieved 12 October 2013 Wood, Jason (1992–93). "Six Northern Castles - A Review of Recent Work Undertaken by the Lancaster University Archaeological Unit". Castle Studies Group Newsletter (6): 18–21. Mackenzie, James D. (1896). The Castles of England: Their Story and Structure. Vol. 2. New York, US: Macmillan. OCLC504892038. Pettifer, Adrian (2002). English Castles: A Guide by Counties. Woodbridge, UK: Boydell Press. ISBN978-0-85115-782-5.
Wood 1992-93, p. 18; Mackenzie 1896, p. 186; Pettifer 2002, p. 272; "List Entry Summary: Piel Castle", English Heritage, archived from the original on 24 October 2014, retrieved 12 October 2013 Wood, Jason (1992–93). "Six Northern Castles - A Review of Recent Work Undertaken by the Lancaster University Archaeological Unit". Castle Studies Group Newsletter (6): 18–21. Mackenzie, James D. (1896). The Castles of England: Their Story and Structure. Vol. 2. New York, US: Macmillan. OCLC504892038. Pettifer, Adrian (2002). English Castles: A Guide by Counties. Woodbridge, UK: Boydell Press. ISBN978-0-85115-782-5.
"Piel Island", Borough of Barrow-in-Furness, archived from the original on 19 October 2013, retrieved 12 October 2013; Rose 2008b, pp. 39–40 Rose, Susan (2008b). Calais: An English Town in France, 1347-1558. Woodbridge, UK: Boydell Press. ISBN9781843834014.
Wood 1992-93, p. 18; Mackenzie 1896, p. 186; Pettifer 2002, p. 272; "List Entry Summary: Piel Castle", English Heritage, archived from the original on 24 October 2014, retrieved 12 October 2013 Wood, Jason (1992–93). "Six Northern Castles - A Review of Recent Work Undertaken by the Lancaster University Archaeological Unit". Castle Studies Group Newsletter (6): 18–21. Mackenzie, James D. (1896). The Castles of England: Their Story and Structure. Vol. 2. New York, US: Macmillan. OCLC504892038. Pettifer, Adrian (2002). English Castles: A Guide by Counties. Woodbridge, UK: Boydell Press. ISBN978-0-85115-782-5.
Raymond 2009, p. 231 Raymond, Michael David (2009). John Wordsworth on Snowdon: The Elegiac Sublime and the Spectacle of Woe (PhD). Fordham University, New York. OCLC727840175.