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:However, just as in the research results demonstrated by Murugappan et al. (Murugappan et al., 2007), (Murugappan et al., 2010), our classification results also indicate that the accuracy can be improved by covering the entire area with more EEG electrodes.
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