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 OHC lateral wall, where the motor elements are located [24,31], was modeled as a series mixture of passive ‘‘elastic’’ and active piezoelectric ‘‘motor’’ elements [29] to arrive at a composite constitutive model for the lateral wall.
Category: