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:non-kin nest burrows, including in long-term data sets (King 1989b; Viblanc et al. 2010; Arnaud, Dobson & Murie 2012; Dobson et al. 2012).
Category: