Cite the scanned version of the original dicionary like this:
Toller, T. Northcote, and Joseph Bosworth. "Ælfric." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth : Supplement. Oxford: Clarendon Press, 1921. 15.
, es; m. [ælf, ríc] Ælfric; Ælfricus. 1. Ælfric of Canterbury, the grammarian, was of noble birth, supposed to be the son of the earl of Kent. He was a scholar of Athelwold, at Abingdon, about 960. When Athelwold was made bishop of Winchester, he took Ælfric with him and made him a priest of his cathedral. Ælfric left Winchester about 988 for Cerne in Dorsetshire, where an abbey was established by Æthelmær. Ic Ælfríc, munuc and mæssepreóst...