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:Other PROs included the Functional Assessment of Chronic Illness Therapy–Fatigue (FACIT-F) scale [24]; morning stiffness, measured by its severity on a 0-mm (no problem) to 100-mm (major problem) VAS [25]; the Rheumatoid Arthritis Impact of Disease (RAID) questionnaire [26]; and the RA-specific Work Productivity Survey (WPS-RA) [27].
Category: