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:Furthermore, methods to detect recently described cfr- or L4 protein-mediated resistances were applied using techniques reported earlier (Arias et al., 2008; Kehrenberg et al., 2005, 2007; Kehrenberg and Schwarz, 2006; Long et al., 2006; Mendes et al., 2008; Schwarz et al., 2000; Toh et al., 2007).
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