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:Groups of similar sequences (greater than 97% identity), which will be referred in this work as OTUs (Operational Taxonomic Units), were identified by building distance (neighbour joining) trees using the software Clustal X v.1.82 (Thompson et al. 1997).
Category: