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:Genes coding for proteins with the GG(D/E)EF and E(A/V)L sequence motifs were identified with PSI-BLAST [38] using reference sequences available at NCBI Gene Entrez [39] [See Additional file 1], against the three K. pneumoniae genomes.
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