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:Hemicellulose hydrolysates contain high amounts (up to 20–30%) of xylose and arabinose (Hahn-Hägerdal et al. 2006; Leandro et al. 2008; Hector et al. 2008).
Category: