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:Each of the individual components of the de novo Fe-S biosynthesis complex (Isu/Iscu, IscS and Isd11) has been proposed to be the molecular adaptor for frataxin interaction [6,11,12,14,15,22].
Category: