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:When the findings are compared to results obtained for organic strawberries and table grapes by Arce (2010), Cerda et al. (2012) and Cerda et al. (2011), it is evident that the calculated WTPs vary considerably among different types of fruit.
Category: