This might be just a supplemental entry adding to an entry in the Main Volume.
Cealca-ceaster
.Add :-- Heó gewát tó þǽre ceastre þe in Englisc is háten Cealcaceaster (Kalca-, v. l.) secessit ad ciuitatem Calcariam, quae a gente Anglorum Kælcacaestir appellatur, Bd. 4, 23; Sch. 466, 15.
Cite the scanned version of the original dicionary like this:
Toller, T. Northcote, and Joseph Bosworth. "Cealca-ceaster." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth : Supplement. Oxford: Clarendon Press, 1921. 118.