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:Other studies indicate that methyl salicylate (MeSA) azelaic acid (AA), glycerol-3-phospate (G3P)derived factor, and dehydroabietinal (DA) may also be SAR long distance signals (Park et al., 2007; Vlot et al., 2008; Jung et al., 2009; Chanda et al., 2011; Chaturvedi et al., 2012).
Category: