Cite the scanned version of the original dicionary like this:
Toller, T. Northcote, and Joseph Bosworth. "neáh-mǽg." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth : Supplement. Oxford: Clarendon Press, 1921. 648.
, neá-, néh-mǽg, es; m. A near kinsman :-- His gebróðru and his neámágas fratres ejus omnisque cognatio illa, Ex. 1, 6. Neáhmága adfinium, Wrt. Voc. ii. 3, 8. His néhmága sum and his worldfreónda, Blickl. Homl. 113, 9. Se man leóf his néhmágum and his worldfreóndum, 111, 27. Wífe and cildan and néhmágon (MS. B. neáhmágum), L. C. S. 71 ; Th. i. 414, 1. [Icel. ná-mágr a near kinsman by marriage.]