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:Moreover, the risk of developing melanoma is greater in males than in females over the age of 40, although the opposite effect is observed in patients under 40 years old (Lens and Dawes, 2004; Jemal et al., 2010).
Category: