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:For example, collagen fibers lack proper organization in the skin and tendons of TSP2-null mice, with underlying fibrils being loosely packed with larger than normal diameters and nonuniform cross-sections (Bornstein et al., 2000; Kyriakides et al., 1998).
Category: