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 degenerated primers were designed from conserved regions in the primary structure of urease sequences from the heterobasidiomycete F. neoformans (Cox et al. 2000) and the ascomycetes C. immitis (Yu et al. 1997) and S. pombe (Tange and Niwa 1997).
Category: