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 addition, the P-VS profiles of SA1 and SA2 have only one inflection point, at the onset of the average Si-O coordination number’s increase from 6 to 6+ (Brazhkin et al. 2011; Wu et al. 2012; Murakami and Bass 2010, 2011).
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