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:Oxidative damage of telomeres along with a general damage of DNA because of aged and thereby inefficient mitochondria could be an explanation (Chen et al., 1995), although contradictory results have been published on this matter (von Zglinicki et al., 2000; Britt-Compton et al., 2009).
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