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:For a close and equitable comparison with other systems based on the same biologically motivated model, we chose to do our experiments on the Caltech-101 database [7], which has become a de facto standard for evaluating algorithms for multiclass category-level recognition, though it lacks in several important sources of intra-class variability [8].
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