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:These morphologic findings in nonhuman primate fetuses are comparable with early anatomic descriptions of the DV morphology in human fetuses.(9,11,14,15) The intrahepatic BPV in nonhuman primate fetuses possess a well-organized media with a higher density of smooth muscle cells than the isthmic portion of the DV.
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