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:DBMM is extensively evaluated in terms of classification performance on two benchmark databases (detailed in (Ullah et al 2008) and (Pronobis et al 2010) respectively) with laserscanner data collected from mobile robots navigating in indoor scenarios.
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