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:%) was a close relative (at 97% identity) of the facultative denitrifying bacterium Aromatoleum aromaticum (which belongs to the Azoarcus cluster) (Kuhner et al., 2005), and the close relative Azoarcus buckelii (Mechichi et al., 2002).
Category: