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:A selection of real-time beat tracking algorithms have been developed that might be suitable for such a task, including B-Keeper [19], a specialised drum tracking system, IBT∼ [20], a multi-agent system based on Dixon’s Beatroot [21], and btrack∼ [7] and beatseeker∼ [8] which use autocorrelation.
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