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 3D plot obtained from raw meat sample (Figure 1A) showed a prominent peak at about 295 nm for 1λ = 40 nm, originating from the fluorescence of protein tryptophan residues (Boubellouta and Dufour 2008).
Category: