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:…(Aldehni et al., 2003), glnN displays an imperfect NtcAbinding motif and a negatively acting cis-element in the upstream region of its promoter (Aldehni & Forchhammer, 2006), and nblA has a complex regulatory region containing multiple promoters: under nitrogen deprivation, its major promoter…
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