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:Interestingly, it plays only an inferior role in the NHFS([9]) and is not included in the POSSUM system.([12]) In summary, given the importance of cognitive ability, assessing cognitive ability must become part of the clinical routine.
Category: