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:Comparison of relative testes size across 24 lemur species revealed that fork-marked lemurs had small testes, as did all pair-living species in this sample and as do pair-living primates in general (Harcourt et al. 1981; Harvey and Harcourt 1984; Kappeler 1997a).
Category: