Jelaskan Catatan dari Gruoch dari Skotlandia

Duncan, A. A. M., The Kingship of the Scots 842–1292: Succession and Independence. Edinburgh University Press, Edinburgh, 2002. ISBN 0-7486-1626-8

Woolf, Alex, "Macbeth" in Michael Lynch (ed.), The Oxford Companion to Scottish History. Oxford UP, Oxford, 2001. ISBN 0-19-211696-7