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:Regarding synthetic inhibitors, PC190723 is the most studied compound so far (Haydon et al., 2008, 2010; Andreu et al., 2010; Adams et al., 2011; Elsen et al., 2012; Tan et al., 2012).
Category: