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:Although it forms the largest ethnic minority group in the UK, the Asian community is not a culturally homogeneous group, a fact that has not been addressed in previous studies of childhood cancer in Asians (Stiller et al., 1991; Powell et al., 1994).
Category: