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:3, 4, this study), have been linked repeatedly to observed UV-B-induced reductions in herbivory, larval development and larval survivorship (McCloud and Berenbaum 1994; Ballaré et al. 1996; Grant Petersson and Renwick 1996; Lindroth et al. 2000; Rousseaux et al. 2004).
Category: