Original sources and the editions used in the text and timelines:
AASB – Acts of the abbots of St Bertin by Folcwin. EHD Secular narrative sources 26, Whitelock 1979.
AC – The Annales Cambriae. Morris 1980.
AClon – Annals of Clonmacnoise. https://www.ucc.ie/celt/transpage.html
Æðelweard – Chronicon. Campbell 1962.
AFM – Annals of the Four Masters. https://www.ucc.ie/celt/online/T100005A
Alcuin Ep – The epistolae of Alcuin. Allott 1974.
APF – Armes Prydein Fawr. Isaac 2007.
ASB – The Annals of St Bertin. Nelson 1991.
ASC – Anglo-Saxon Chronicle. Garmonsway 1972.
Asser – Life of King Alfred. Keynes and Lapidge 1983.
AU – Annals of Ulster. http://www.ucc.ie/celt/online/T100001A.
CKA – Chronicle of the Kings of Alba. Woolf 2007.
Egil’s Saga – Scudder and Óskarsdóttir 2004.
EHD – English Historical Documents volume 1. Whitelock 1979.
FoW – Florence of Worcester : the reigns of the Danish kings of England. EHD Secular narrative sources 9. Whitelock 1979.
Fragmentary Annals – Wainright 1975b.
Gesta Regum Anglorum – William of Malmesbury. Giles 1847 and EHD Secular narrative sources 8. Whitelock 1979.
HE – Bede’s Historia Ecclesiastica. Colgrave and Mynors 1969.
Historia Abbatum – Webb and Farmer 1983.
HR – Historia Regum. EHD Secular narrative sources 3. Whitelock 1979.
HSC – Historia de Sancto Cuthberto. South 2002.
LDE – Symeon’s Libellus de Exordio. Stephenson 1993.
Liber Eliensis – Fairweather 2005.
Nithard’s Histories – Scholz 1972.
Orkneyinga Saga – Pálsson and Edwards 1981.
Poetic Edda – Larrington 2014.
Prose Edda – Bycock 2005.
RFA – Royal Frankish Annals. Scholz 1972.
RoW – Roger of Wendover: Flores Historiarum. Giles 1849.
VC – Vita Colombae. Adomnán’s Life of St Columba. Sharpe 1995.
VW – Eddius Stephanus’s Vita Wilfridi. Webb and Farmer 1983.
Charters are referenced by their S- (Sawyer) number, which can be used to search for them in the online resource called the Electronic Sawyer: http://www.esawyer.org.uk/about/index.html.