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:…memory in aMCI and AD patients has been extensively reported (Brown & Storandt, 2000; Carlesimo et al., 2011; Grober & Kawas, 1997; Grober et al., 2008; Ivanoiu et al., 2005; Lemos et al., 2015; Mahieux et al., 2009; Saka et al., 2006; Sarazin et al., 2010; Vogel et al., 2007; Wagner et al., 2012).
Category: