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:In support of this assumption, in ARDS patients, TRAIL levels in the BAL fluid were correlated with clinical severity and the presence of neutrophils, which are also the major infiltrating cells in reovirus 1/L-induced ARDS (20, 84).
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