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:[4] The use of multiple maneuvers including swallowing water, separate-day imaging, oblique and lateral imaging, correlating with other imaging techniques, is essential for accurate diagnosis.[26] In the current study physical examinations revealed no palpable midline neck mass in any of the subjects, and postoperative US revealed no abnormally enlarged lymph nodes in the central compartment of the anterior neck.
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