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:As reported by others (Roshan et al. 2003; Fisher et al. 2002), the results of SICI with threshold tracking showed two periods of maximal inhibition at ISIs 1 and 3 ms.
Category: