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:After 30 min, ATP was added as described in step 2; (5) steps 3 and 4 were repeated sequentially using the desired immobilized di- or tri- blocks; (6) after three washing steps with buffer B and 3 more with buffer A, the synthesized chain was released with either SfiI (New England Biolabs) to allow subcloning in the shuttle plasmid pAPG10, or by sequential SfaNI, wash, BbvI digestions to allow subcloning in plasmids already containing a TALEN scaffold.
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