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 physical component score (PCS) and mental component score (MCS) from the SF-12 were compared to those obtained from the 1998 National Survey of Functional Health Status.(15) Additionally, an addendum questionnaire (AQ) was administered to LDs after the SF-12 questionnaire.
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