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:8) on the MMSE), diagnosed with amnestic MCI based on the Petersen criteria (Petersen et al. 1999); and 16 CN subjects (mean age 73(9) years; mean score 29.
Category: