| Sources |
- [S55] English Baronies, Blythborough, Suffolk barony, p. 16 (Reliability: 3).
- [S55] English Baronies, Whalton, Northumberland barony (2nd class), p. 150 (Reliability: 3).
- [S19] rootsweb, Mark Willis-Ballard.
- [S72] II: Domesday Descendants, His father, Roger filius Ricardi de Wrkewrthe, p. 948 (Reliability: 3).
- [S72] II: Domesday Descendants, His wife, Margaret filia Willelmi Vicecomitis, p. 1138 (Reliability: 3).
- [S13] bright.ged.
- [S20] gen_bursonram_A.ged, downloaded de.2005.
- [S47] PL_4_WWW_all.ged, downloaded april 2006.
- [S49] Complete Peerage, Early Veres, Vol X, Appx J, p.110 seq (Reliability: 3).
- [S49] Complete Peerage, Engaine article, Vol V, chart betw. pp. 72 & 73 (Reliability: 3).
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