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 same result is predicted by conventional theories of magnetic polarons in 2D [9, 11, 12]; But in that case the severe modification of the bandwidth of the hole, from 8t for a free holon to an expression ‚àù Jx, is usually interpreted as a consequence of strong polaronic mass renormalization.
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