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:br A recent work (Bhuiyan et al., 2004) in the SCNT bovine field demonstrated that transfected ear fibroblasts were less able to develop to the blastocyst stage than their non-transfected counterpart, regardless of passage number (early or late).
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