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:However, in the case of RCG-dominated wetlands, Askaer et al. (2011) found that the diurnal variability of CH4 fluxes was not significant in spite of a significant share of plant-mediated CH4 transport.
Category: