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 DP is a reaction occurring on the catalyst surface between precursors [17,23] (alkoxy/α-hydroxyalkyl and benzyl alcohol), which is known to provide an equimolar quantity of toluene and benzaldehyde in the absence of oxygen, according to the following surface reaction:
Category: