Burke, B. (1814–1892), A genealogical and heraldic dictionary of the peerage and baronetage of the British Empire (1869) p.670 online version
See Capgrave, The book of illustrious Henries, On-line version
british-history.ac.uk
"Henry de Exon 1353-?, By exch. with Geoffrey de Cornasano for a canonry with reservn. of preb. in Lanchester colleg. ch., co. Dur., 12 March 1353 (CPL. 11 482; see above p. 32)." (from: 'Canons of Llandaff', Fasti Ecclesiae Anglicanae 1300–1541: volume 11: The Welsh dioceses (Bangor, Llandaff, St Asaph, St Davids) (1965), pp. 32-34, compid=32454&strquery=llandaff On-line version Date accessed: 13 June 2010.