Cite the scanned version of the original dicionary like this:
Bosworth, Joseph. "gang-tún." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth. Ed. Thomas Northcote Toller. Oxford: Clarendon Press, 1898. 361.
.Add: A draught-house :-- Hí worhton ánne gangtún þǽr ðǽr se god Baal ǽr wæs gewurðod (they brake down the house of Baal, and made it a draught-house; fecerunt pro æde Baal latrinas, 2 Kings 10, 27), Hml. S. 18, 379.