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:Relative contribution of P450 1A5 and 3A37 in the epoxidation of AFB1 to exo-AFBO
The epoxidation of AFB1 to form exo-AFBO is themost critical step in the toxic and carcinogenic effects of this mycotoxin (Rawal et al., 2010b).
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