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:They separated at a 40–50% higher molecular weight than calculated from their sequence (Figure 1A, right), which is in agreement with earlier studies (Maas et al., 2000; Weissmann et al., 2009).
Category: