Cite the scanned version of the original dicionary like this:
Toller, T. Northcote, and Joseph Bosworth. "tín-wintre." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth : Supplement. Oxford: Clarendon Press, 1921. 722.
;adj. Ten years old :-- .x. wintre cniht mæg bión þiéfðe gewita a ten year old boy can be accessory to a theft, L. In. 7; Th. i. 106, 18. Ðá ða hé týnwintre on ylde wæs, Homl. Th. ii. 498, 28.