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:It was estimated that among a total of 288,009 hospitalized survivors of neurotrauma in the United States in 2003, 124,626 patients developed long-term disability resulting in significant demand on rehabilitation services (Selassie et al., 2008).
Category: