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:These results are higher than the percentages obtained by other studies such as 18.3% by Konuma et al. (1988), 28% by Schlegelova et al. (2003) and 30.85% by Tewari et al. (2012).
Category: