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:…depression among gay and HIVpositive men (Körner et al. 2008; Newman et al. 2008; Newman et al. 2009), the contributory role of male sexual dysfunction to depression (Mao et al. 2009a), and the difficulties of managing depression among men who use crystal methamphetamine (Saltman et al. 2008).
Category: