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:On contrary to our results, Huang et al. (2006) studied 150 Chinese patients with SLE and 130 unrelated healthy individuals living in central Taiwan as control subjects. There were no statistically significant differences in IL-6 and IL-8 gene polymorphisms between the SLE and control groups (p=0.53 and p=0.44, respectively). In addition, there was no significant association between the two groups in allelic frequency of IL-6 and IL-8 (p=0.89 and p=0.26, respectively). Also, Schotte et al. (2001) studied a population-based case–control study of 211 Caucasian German SLE patients and did not reveal any significant association of IL-6 gene polymorphism with susceptibility to SLE.
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