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:Either explanation (DIR1 dimers or DIR1-protein complexes) fits with the appearance of trypsin-sensitive high molecular weight fractions in dehydroabietinal-elicited SAR observed by Chaturvedi et al. (2012).
Category: