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:This finding extends previous work that has shown that certain aspects of gait may depend on cognitive function and attention (Springer et al. 2006; Woollacott and Shumway-Cook 2002; Yogev et al. 2005; Bloem et al. 2001; Morris et al. 1996; Auriel et al. 2006; Van Wegen et al. 2006; Verghese et al. 2002).
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