Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Interregional GABAergic neurons have been described also in the adult isocortex (Gonchar et al., 1995; Fabri and Manzoni, 1996; Jinno and Kosaka, 2004; Tomioka et al., 2005; Apergis-
 Schoute et al., 2007).
Category: