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 result differs from the findings of a study of great tits where birds with highest H/L ratios at capture (indicating higher stress level, Davis et al. 2008) inflicted the maximum extent of tail damage during the week spent in captivity (Krams et al. 2013).
Category: