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:…and Konofagou 2014; Choi et al. 2010b), chemotherapy agents (Aryal et al. 2013; Treat et al. 2007; Treat et al. 2012; Yang et al. 2012), antibodies (Kinoshita et al. 2006), magnetic nanoparticles (Fan et al. 2013), gene therapy vectors (Alonso et al. 2013), stem cells (Burgess et al. 2011) etc.
Category: