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:approach used in several instances of previous work, such as [2, 8, 35], by hiding unchanged nodes to reduce clutter and drawing connectors to the reference to enhance juxtaposition; b) side-byside views [14, 26, 27] by going beyond pair-wise comparisons; c) existing work on subjunctive interfaces [30], TreeVersity [15– 17, 19] and TreeVersity2 [18, 19] to show a larger variety of difference visualizations.
Category: