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:This putative association of Rho with RNA polymerase (RNAP) in vivo was first inferred from a ChIP-chip experiment (Mooney et al., 2009) and later from in vitro measurements (Epshtein
et al., 2010).
Category: