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:(Chen et al., 2009; de Bruijn et al., 2002; Sugiyama et al., 2003; Zovein et al., 2008) species indicate that IAHCs derive from hemogenic ECs through an Endothelial-to-Hematopoietic Transition (EHT).
Category: