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:We augment phrase tables only with synthetic phrases that capture simulated ASR errors, the methodology that we advocate, however, is applicable to many problems in translation (Tsvetkov et al., 2013a; Ammar et al., 2013; Chahuneau et al., 2013).
Category: