Cite the scanned version of the original dicionary like this:
Toller, T. Northcote, and Joseph Bosworth. "níd-þeów." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth : Supplement. Oxford: Clarendon Press, 1921. 651.
, es; m. A slave, thrall :-- Wé ðé, Hǽlend, biddaþ ðæt ðú gehýre hæfta stefne ðínra niédþiówa, Exon. Th. 22, 33; Cri. 361. Ne derige se hláford his mannum, ne forðan his nýdþeówan, L. I. P. 7; Th. ii. 314, 3. v. next word.