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: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: