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 lesions with pure SEF morphology (90% of patients), feature that has not been documented previously in the largest SEF series published to date (Meis-Kindblom et al., 1995; Doyle et al., 2012; Wang et al., 2012), except for a slight female tendency in Antonescu et al. (2001) SEF cohort, in…
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