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:Effects of CACC inhibitors were analyzed by the following four-parameter logistic function: y min (max min)/[1 (x/IC50) Hill slope], where min and max are the bottom and top of the curve, respectively, IC50 is the concentration of half inhibition of block, and the Hill slope is a reflection of the steepness of the curve.
Category: