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:In contrast, our analysis of the binding sites of 34 TFs revealed that many iUCEs likely serve as enhancers in early fly development, similarly to what has been observed in mammals (Pennacchio et al. 2006; Visel et al. 2008).
Category: