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:Bacterial strains and growth conditions The genome sequences of B. pertussis TohamaI, Bordetella parapertussis 12822, Bordetella bronchesipteca RB50 [34] and Bordetella avium N197 [35] were used in the computational analyses.
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