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:To facilitate detection of metagenomic SSU rRNA sequences matching sequences in the SILVA database (release 126) [12], all bacterial SSU rRNA sequences ≥ 1200 bp deposited in the SILVA database (release 126) [12] were added to the initial data set and a second clustering at 97% and consecutively 85% sequence similarity threshold was performed (version 9.
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