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:The reversible Michaelis-Menten kinetics is a three-step mechanism containing three separate steps: (i) binding the enzyme E to the substrate S, (ii) the reversible catalytic conversion between the enzyme-substrate ES and the enzyme-product EP complexes, and (iii) binding of the enzyme E to product P (Heinrich and Schuster, 1996).
Category: