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 noted by Schoonbaert and Grainger (2004) and by Dehaene et al. (2005), in models using open-bigram coding schemes (Grainger & van Heuven, 2003; Whitney, 2001), repeated letters imply repetition at the bigram level.
Category: