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:In agreement with previous reports that support DNA molecules as both spacer donors and interference targets (Barrangou et al., 2007; Brouns et al., 2008; Lillestøl et al., 2006; Marraffini & Sontheimer, 2008; Mojica et al., 2009; Semenova et al., 2009; Vestergaard et al., 2008), given a common point of reference for orientation of spacers, proto-spacers match both strands of the carrier DNA molecule and any direction of transcription, and are found even in non-coding regions (see Fig.
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