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:This strain shows accelerated age-related hearing loss (Henry and Chole, 1980; Hunter and Willott, 1987; Mikaelian, 1979; Spongr et al., 1997; Willott, 1986).
Category: