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:However, giant panda habitat analyses have been performed mainly inside nature reserves (Linderman et al., 2005; Liu et al., 1999, 2001, 2005; Viña et al., 2007, 2008) or within single mountain regions (Feng et al., 2009; Loucks et al., 2003; Shen et al., 2008; Xu et al., 2006) and often using…
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