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:A geriatrician or neurologist diagnosed AD using the criteria devised by the National Institute of Neurological and Communicative Disorders and Stroke and AD and Related Disorders Association (NINCDS-ADRDA), and the Diagnostic and Statistical manual of Mental Disorders (DSM-IV) [3, 20].
Category: