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 result is consistent with findings by Bland et al.21
 Several ultrasonography studies after carpal tunnel release have been reported previously.13,14,22‚Äì25 However, the clinical significance of a reduction in the CSA after carpal tunnel release remains controversial.
Category: