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:Stem Cell Reports This is an open access arti without the use of transgenes remain dependent on fibroblast growth factor (FGF) or transforming growth factor b (TGF-b) (Chan et al., 2013; Gafni et al., 2013; Valamehr et al., 2014; Ware et al., 2014; Duggal et al., 2015; Qin et al., 2016), which is a major property of the primed state (Vallier et al.
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