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:Several routing schemes as surveyed in [16] adopt the planar graph [24] derived from the unit disk graph (UDG) as their network topologies, such as GPSR [3], GFG [17], Compass Routing II [18], AFR [19], GOAFR [20] GOAFR+ [21], GOAFR++ [16], and GPVFR [22].
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