Edmund of Langley, earl of Cambridge (d. 1402)
Edmund of Langley, earl of Cambridge (1341 - 1402), duke of York; fifth son of Edward III, king of England, earl of Cambridge and later duke of York, uncle of king Richard II.
Anthony Tuck, ‘Edmund, first duke of York (1341–1402)’, in Oxford dictionary of national biography, ed. by H. C. G. Matthew and Brian Harrison (Oxford: Oxford University Press, 2004), pp. http://www.oxforddnb.com/view/article/16023.
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