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:…protein pattern differential analysis
Total proteins were extracted from the shoots of two biological replicates corresponding to different pots (for treatments i, ii, and iii) and separated by 2-DE; MS/MS analysis and protein identification were performed as described in Farinati et al. (2009).
Category: