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:In this chapter, we focus on the use of two-photon laser scanning microscopy, which has enabled the monitoring of hundreds of individual neurons in anesthetized (26), awake and behaving animals (9, 11, 27, 28) as well as neurotransmitter uncaging at the level of individual dendritic spines (29, 30) or at many discrete sites simultaneously (15).
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