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:In addition, we have analysed the activity of JEV NS2B(H)-NS3pro by using a tetrabasic internally quenched fluorescent peptide, Abz-(R)4SAGnY-amide, originally described for the DEN NS3 serine protease [22].
Category: