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:It has been reported that SB243213, a selective 5-HT2C neutral antagonist (Bromidge et al. 2000), reversed the subchronic PCP-induced impairment in rat reversal learning (McLean et al. 2009a).
Category: