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:Methods for extraction, amplification and sequencing of the nuclear 5.8S rRNA gene and the two flanking, ITS regions were as previously published (Ganley et al., 2004; Shipunov et al., 2008).
Category: