Cite the scanned version of the original dicionary like this:
Bosworth, Joseph. "deorcian." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth. Ed. Thomas Northcote Toller. Oxford: Clarendon Press, 1898. 202.
.Substitute: To become dark, to grow dim (of sight) :-- Deorcaþ gesihð hebet visus, Ps. L. fol. 142, 2. [Hise iȝen derkeden (caligaverant), Wick. i. Sam. 4, 15. v. N. E. D. dark; vb.] v. á-deorcian.