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:Identifying a Mu insertion genetically linked to a mutant phenotype
We initially developed the method using an empty pericarp mutant, emp*02S-0422 (Figure 2), obtained from the UniformMu collection (McCarty et al., 2005; Settles et al., 2007).
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