Cite the scanned version of the original dicionary like this:
Toller, T. Northcote, and Joseph Bosworth. "cásering." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth : Supplement. Oxford: Clarendon Press, 1921. 118.
, e; f. A cæsaring, a coin with an emperor's image, a coin; drachma = δραχμή , didrachma :-- Gif wíf losaþ cásering si mulier perdiderit drachmam. Lk. Lind. Rush. War. 15, 8. Ne unband cásering non solvit didrachma, Mt. Lind. Stv. 17, 23.