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:TfMA had lower sequence identity of 33~27% with α-amylase II from Thermoactinomyces vulgaris (Tonozuka et al. 1993), maltogenic amylase from Thermus sp. IM6501 (Kim et al. 1999), neopullulanase from Geobacillus stearothermophilus (Cheong et al. 2002), glucosidase from Thermotoga maritima (Lee et…
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