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:…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. Fisher et al. (2002) demonstrated peaks at 1 ms and between 2.2 and 2.8 ms while Roshan et al. (2003) found peaks of inhibition at 1 and 2.5 ms.
Category: