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:Recently, several groups have reported the conversion of hPSCs from a primed to a naive state (Hanna et al., 2010; Gafni et al., 2013; Chan et al., 2013; Takashima et al., 2014; Theunissen et al., 2014; Valamehr et al., 2014; Wang et al., 2014; Ware et al., 2014; Chen et al., 2015; Duggal et al., 2015; Hayashi et al., 2015; Qin et al., 2016).
Category: