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:To further investigate the characteristics of the identified adipose unmethylated and low-methylated regions, we used ChIP-seq data from the NIH Roadmap consortium [28] for the active promoter-associated H3K4me3 [29] and the active enhancer-associated H3K4me1 [30] marks in human adipocytes.
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