Cite the scanned version of the original dicionary like this:
Bosworth, Joseph. "ofer-gǽgan." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth. Ed. Thomas Northcote Toller. Oxford: Clarendon Press, 1898. 733.
.Add :-- Gif hwá þis ofergǽgð si quis transgressus fuerit, Chrd. 46, 15. Se cásere hét hine bewǽpnian and beforan his ansýne ætstandan . . . swilce ofergǽgendne his hláfordes bebod, Hml. S. 30, 411.