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, a more stringent microarray experiment found that most of the low fluence rate UV-B induced genes depend on either of the two bZIP transcription factors HY5 and HYH (Oravecz et al. 2006,
Physiol.
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