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:…traditionally put forward as a major biological factor facilitating herbivory and frugivory in lizards (see Schoener et al. 1982; Van Damme 1999; Cooper and Vitt 2002), a recent review of frugivory and seed dispersal by lizards suggested that frugivory should be considered an island phenomenon,…
Category: