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:lingual phrase-based machine translation system with a reranking post-processing step8 (Wubben et al., 2012) and Hybrid, a model which first performs sentence splitting and deletion operations over discourse representation structures and then further simplifies sentences with PBMT-R (Narayan and Gardent, 2014).
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