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:In the present study, only the Zn content was significantly elevated in the plaques at 56 weeks old, further indicating that increased Zn is a late-stage effect of advanced plaque pathology (Religa et al., 2006).
Category: