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:The loss of white matter following injury might be the result of the retraction or degeneration of injured descending fibres (Schwab and Bartholdi 1996), although this typically occurs over only short distances (Schnell and Schwab 1993) and therefore probably does not explain the loss seen in the present study.
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