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:While all of the papers included outcomes, when it came to QOL assessment, 2 of the 38 used SF36 [3, 19, 39] others used FACT-BR [5, 22, 40], and 8 used a more basic patient functionality-oriented Karnofsky Performance Status (KPS) comparison [10, 13, 28, 32, 34, 36, 37], and less than half (15 of 38 papers) utilized any QOL instrument at all (FACT-BR, SF36, KPS Scale, or some other instrument).
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