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:Perceived reachability (PR) is a relatively new concept in IS/IT research, but has been used with research dealing with wireless technology, for example by Kim and Garrison (2009), who were among the first to incorporate PR into the TAM framework.
Category: