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:[21] Bathymetric maps were generated for each Alvin dive, by merging vehicle navigation and attitude data with traveltimes recorded by the sonar through a series of Matlabk programs [Ballard et al., 2000; Singh et al., 2000; Whitcomb et al., 2000; Ferrini et al., 2004, 2005a].
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