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:There are multiple techniques for identifying protein coding genes that are involved in cancer because mutations that occur in protein coding genes can result in missense mutations, and methods have been developed for identifying which of these mutations are drivers as opposed to simply passengers (Carter et al., 2009; Kaminker et al., 2007; Youn & Simon, 2011).
Category: