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:Patients were assessed with the Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD) Affective Disorders Evaluation (Sachs et al., 2002, 2003), which included the mood disorders module of the Structured Clinical Interview for DSM (First et al., 1996) and Clinical Global…
Category: