Cite the scanned version of the original dicionary like this:
Toller, T. Northcote, and Joseph Bosworth. "feald." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth : Supplement. Oxford: Clarendon Press, 1921. 206.
, the termination of numerals, as án-feald one-fold, single; twí-feald or twý-feald two-fold, double; þreó-feald or þrý-feald three-fold, treble; seofon-feald seven-fold; manig-feald manifold. [O. Sax. -fald: O. Frs. -fald: M. H. Ger. -valt: O. H. Ger. -falt: Goth. -falþs.]