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:Archaea were assayed using the primer pairs 20F [61] and 1492R, 20F and 1406R [62], 20F and 519R [63] with the same PCR conditions used to amplify bacterial 16S rDNA, except 40 cycles were used.
Category: