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:Also, functional integration abnormalities between brain areas, which are primarily reflected by the intrinsic functional connectivity, were demonstrated to be the neural basis of impaired cognition in aMCI patients (Bai et al., 2009a, 2009b; Sorg et al., 2007; Xie et al., 2012).
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