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:For the assimilation of SMOS brightness temperature data, VIC is coupled with the Community Microwave Emission Model (CMEM) [3-5], which allows for simulating the Top Of the Atmosphere (TOA) brightness temperature contributions of the different surface covers at the hydrologic model resolution.
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