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:…et al., 2001; Steyn-Ross et al., 2005) to name only a few, their application to anesthetic-induced EEG changes is relatively recent (Bojak and Liley, 2005; Foster et al., 2008; Hutt and Longtin, 2010; Liley and Bojak, 2005; Liley et al., 2003; Molaee-Ardekani et al., 2007; SteynRoss et al., 1999).
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