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:ankle-link antigen (ALA) with ankle links (Goodyear and Richardson, 1999), and the tip-link antigen (TLA) with tip and kinocilial links (Goodyear and Richardson, 2003).
Category: