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:…1988 [42] Manual (IM) postop xray 25 92 Tillett et al. 1988 [42] Manual (IM) postop xray 25 92 Tillett et al. 1988 [42] Manual (EM) postop xray 25 80 Tillett et al. 1988 [42] Manual (EM) postop xray 25 80 Decking et al., 2005 [13] Manual postop xray 25 36 Decking et al. 2005 [13] Manual postop…
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