Cite the scanned version of the original dicionary like this:
Bosworth, Joseph. "æl." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth. Ed. Thomas Northcote Toller. Oxford: Clarendon Press, 1898. 13.
, e; f. Burning :-- Ðára eágan scínað swá leóhte swá is án micel blácern on ǽle (onǽle? cf. on-ál) their eyes shine as bright as is a great lamp a-light, Nar. 37, 18.