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:…94 Hart et al. 2003 [17] Manual postop xray 60 70 Hart et al. 2003 [17] Manual postop xray 60 93 Matsumoto et al. 2004 [27] Manual postop xray 30 67 Tillett et al. 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)…
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