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:Illustra PuReTaq ReadyTo-Go PCR beads (0.5 ml tubes, GE healthcare) were used to amplify DTL, SLFN5, TRIM47, WRAP53 and CHN1 transcripts (denaturing at 94uC for 30 s, annealing at 58uC for 1 min and elongation at 72uC for 2 min, 25‚Äì35 cycles).
Category: