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:…genetic variation, but the disease phenotype does not only result from functional alteration of the affected gene product, perturbations rather spread along the links of the underpinning cellular networks (Schadt 2009; Barabási et al 2011; Menche et al 2015; Piñero et al 2016; Caldera et al 2017).
Category: