Prestwich 2003,第38頁; Phillips 2011,第5頁; Gillingham, John, Hard on Wales, Times Literary Supplement, Times Literary Supplement, 11 July 2008 [22 April 2014], (原始内容存档于2020-03-25)
web.archive.org
Prestwich 2003,第38頁; Phillips 2011,第5頁; Gillingham, John, Hard on Wales, Times Literary Supplement, Times Literary Supplement, 11 July 2008 [22 April 2014], (原始内容存档于2020-03-25)