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:In the model-interpolation method [1], an under-trained triphone is re-tuned by interpolating the model with others of less contextdependency , i.e. the left-context, right-context and/or context-independent models, which can be trained more reliably.
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