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:As for soluble TF, both patient groups differed significantly from the controls (146 [104-188] and 116 [92150] pg/mL in the patient groups, respectively, versus 76 [32-108] in the control group).
Category: