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:Overall Leptospira infection prevalence reported in black rats tested by PCR ranged from 11 0% to 65 8% (n = 6; number of animals: median = 79, range = 33–141) [85, 86, 92, 103, 118, 124].
Category: