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:Transvenous endomyocardial biopsy may be of great help for an in vivo morphological demonstration of fibro-fatty myocardial replacement [10], but recent studies have shown a high degree of interobserver variability in assessing fatty deposition, which may be observed even in normal hearts [1].
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